After 16 Jan 1478 and before 07 Feb 1478. The original act doesn't contain a date. Parliament opened on 16 Jan 1478. On 07 Feb 1478 Henry Stafford 2nd Duke of Buckingham (age 23) was appointed Steward of England for the purpose of effecting the exection. George York 1st Duke of Clarence (age 28) was attainted by Parliament. The wording of the attainder as follows:

The Kyng (age 35), oure Sovereigne Lorde, hath called to his Remembraunce the manyfold grete Conspiracies, malicious and heynous Ttresons, that hertofore hath be compassed by dyverse persones his unnaturall Subgetts, Rebelles and Traytoures, wherby Commocions and Insurrections have been made within this his Royaulme, for entent and purpose to have destroyed his moost Roiall persone, and with that to have subverted the state, wele publique and politic of all his said Royaulme; ne had so been, that by th'elp of Almyghty God, with the grete laboures and diligences and uttermost explette of his persone by Chevalrye and Werr, he had mightly and graciously repressed the same. Wherthrogh grete nowmbre of the said his Rebelles and Traytours he hath at dyverse tymes punysshed, as well by swerd as other punysshments, in exemple to others to have been ware of suche attempting hereafter. And yet as a benigne and a gracious Prince moeved unto pitie, after his grete Victories sent hym by God, not oonly he hath spared the multitudes in theire feldes and assembles overcomen, but thaym and certeyn other, the grete movers, sturters and executours of suche haynous Tresons, at the reverence of God, he hath taken to his mercy and clerly pardoned, as may not be unknowen to all the Worlde.

This notwithstondyng, it is comen nowe of late to his knowlage, howe that agaynst his mooste Royall persone, and agaynst the persones of the blessed Princesse oure alther soveraigne and Liege Lady the Quene, of my Lorde the Prince theire son and Heire, and of all the other of thaire moost noble issue, and also against the grete parte of the Noble of this Lande, the good rule, politike and wele publique of the same, hath been conspired, compassed and purposed a moch higher, moch more malicious, more unnaturall and lothely Treason than atte eny tyme hertoforn hath been compassed, purposed and conspired, from the Kyng's first Reigne hiderto; which Treason is, and must be called, so moche and more henyous, unnaturell and lothely, for that not oonly it hath proceded of the moost extreme purpensed malice, incomparably excedyng eny other that hath been aforn, but also for that it hath been contryved, imagined and conspired, by the persone that of all erthely creatures, beside the dutie of ligeaunce, by nature, by benefette, by gratitude, and by yeftes and grauntes of Goodes and Possessions, hath been moost bounden and behalden to have dradde, loved, honoured, and evere thanked the kyng more largely, than evere was eny other bounden or beholden, whom to name it gretely aggruggeth the hert of oure said Sovereigne Lorde, sauf oonly that he is of necessite compelled, for the suertie, wele and tranquillite of hym and all this Royaulme, which were full neer the poynt of perdicion, ne were the help and grace of Almyghty God:

He sheweth you therefore, that all this hath been entended by his Brother, George, the Duke of Clarence (age 28). Wherein it is to be remembered that the Kynges Highnesse, of tendre youthe unto now of late, hath evere loved and cherysshed hym, as tenderly and as kynderly, as eny creature myght his naturell Brother, as well it may be declared, by that that he beyng right yonge, not borne to have eny lifelode, butt oonly of the Kynges grace he yave hym soo large porcion of Possessions that noo memorie is of, or seldom hath been seen, that eny Kyng of Englande hertoforn within his Royaulme yave soo largely to eny his Brothers. And not oonly that, butt above that, he furnyssed hym plenteously of all manere stuff, that to a right grete Prynce myght well suffice; so that aftre the Kynges, his lifelode and richesse notably exceded any other within his Lande at thatt tyme.

And yet the kyng, not herewith content, butt beyng ryght desirous to make hym of myght and puissance excedyng others, caused the greate parte of all the Nobles of this Lande to be assured unto hym next his Highnesse; trustyng that not oonly by the bond of nature, butt also by the bondes of soo grete benefitt, he shulde be more than others loving, helping, assisting and obeissaunt to all the Kyngs good pleasures and commaundments, and to all that myght be to the politik wele of his Lande.

All this notwithstondyng, it is to remember, the large grace and foryevnesse that he yave hym uppon, and for that at dyverse tyme sith he gretely offended the Kyng, as in jupartyng the Kyngs Royall estate, persone and life, in straite warde, puttyng hym thereby from all his libertie, aftre procuryng grete Commocions, and sith the voydaunce oute of his Royaulme, assistyng yevyng to his enemies mortall, the usurpers, laboryng also by Parlement to exclude hym and all his from the Regalie, and enabling hymself to the same, and by dyverse weyes otherwyse attemptyng; which all the Kyng, by nature and love moeved, utterly foryave, entendyng to have putte all in perpetuell oblivion.

The said Duke, nathelesse for all this, noo love encreasyng, but growyng daily in more and more malice, hath not left to consedre and conspire newe Treasons, more haynous and lothely than ever aforn, how that the said Duke falsly and traitrously entended, and puposed fermely, th'extreme distruction and disherityng of the Kyng and his Issue, and to subverte all the polityk rule of this Royaulme, by myght to be goten as well outewarde as inward, which false purpose the rather to brynge aboute, he cast and compassed the moyans to enduce the Kynges naturell Subgetts to withdrawe theire herts, loves and affections from the Kyng, theire naturell Sovereigne Lorde, by many subtill, contryved weyes, as in causyng dyverse his Servauntes, suche as he coude imagyne moste apte to sowe sedicion and aggrugge amonge the People, to goo into diverse parties of this Royaulme, and to laboure to enforme the People largely in every place where they shulde come, that Thomas Burdett, his Servaunte, which was lawefully and truly atteynted of Treason, was wrongefully putte to Deth; to some his Servauntes of suche like disposicion, he yave large Money, Veneson, therewith to assemble the Kynges Subgects to Feste theym and chere theym, and by theire policies and resonyng, enduce hem to beleve that the said Burdett was wrongfully executed, and so to putte it in noyse and herts of the People;

he saide and laboured also to be noysed by such his Servauntez apte for that werk, that the Kyng, oure Sovereigne Lorde, wroght by Nygromancye, and used Crafte to poyson his Subgettes, suche as hym pleased; to th'entent to desclaundre the Kyng in the moost haynous wyse he couth in the sight and conceipt of his Subgetts, and thefore to encorage theym to hate, despice and aggrugge theire herts agaynst hym, thynkyng that he ne lived ne dealid with his Subgettes as a Christien Prynce.

And overe this, the said duke beyng in full purpose to exalte hymself and his Heires to the Regallye and Corone of Englande, and clerely in opinion to putte aside from the same for ever the said Corone from the Kyng and his Heirez, uppon oon the falsest and moost unnaturall coloured pretense that man myght imagine, falsely and untruely noysed, published and saide, that the Kyng oure Sovereigne Lorde was a Bastard, and not begottone to reigne uppon us; and to contynue and procede ferther in this his moost malicious and traytorous purpose, after this lothely, false and sedicious langage shewed and declared amonge the People, he enduced dyverse of the Kynges naturall Subgetts to be sworne uppon the blessed Sacrament to be true to hym and his heires, noon exception reserved of theire liegeaunce; and after the same Othe soo made, he shewed to many other, and to certayn persones, that suche Othe had made, that the Kyng had taken his lifelode from hym and his men, and disheryed theym, and he wolde utterly endevoire hym to gete hem theire enheritaunce as he wolde doo for his owen.

He shewed also that the Kyng entended to consume hym in like wyse as a Candell consumeth in brennyng, wherof he wolde in brief tyme quyte hym. And overe this, the said Duke continuyng ín his false purpose, opteyned and gate an exemplificacion undre the Grete Seall of Herry the Sexte, late in dede and not in right Kyng of this Lande, wherin were conteyned alle suche appoyntements as late was made betwene the said Duke and Margaret, callyng herself Quene of this Lande, and other; amonges whiche it was conteyned, that if the said Herry, and Edward, his first begoton Son, died withoute Issue Male of theire Bodye, that the seid Duke and his Heires shulde be Kyng of this Lande; which exemplificacion the said Duke hath kepyd with hymself secrete, not doyng the Kyng to have eny knowlegge therof, therby to have abused the Kynges true Subgetts for the rather execucion of his said false purpose.

And also, the same Duke purposyng to accomplisse his said false and untrue entent, and to inquiete and trouble the Kynge, oure said Sovereigne Lorde, his Leige People and this his Royaulme, nowe of late willed and desired the Abbot of Tweybury, Mayster John Tapton, Clerk, and Roger Harewell Esquier, to cause a straunge childe to have be brought into his Castell of Warwyk, and there to have beputte and kept in likelinesse of his Sonne and Heire, and that they shulde have conveyed and sent his said Sonne and Heire into Ireland, or into Flaundres, oute of this Lande, whereby he myght have goten hym assistaunce and favoure agaynst oure said Sovereigne Lorde; and for the execucion of the same, sent oon John Taylour, his Servaunte, to have had delyveraunce of his said Sonne and Heire, for to have conveyed hym; the whiche Mayster John Tapton and Roger Harewell denyed the delyveraunce of the said Childe, and soo by Goddes grace his said false and untrue entent was lette and undoon.

And also, the same Duke purposyng to accomplisse his said false and untrue entent, and to inquiete and trouble the Kynge, oure said Sovereigne Lorde, his Leige People and this his Royaulme, nowe of late willed and desired the Abbot of Tweybury, Mayster John Tapton, Clerk, and Roger Harewell Esquier, to cause a straunge childe to have be brought into his Castell of Warwyk, and there to have beputte and kept in likelinesse of his Sonne and Heire, and that they shulde have conveyed and sent his said Sonne and Heire into Ireland, or into Flaundres, oute of this Lande, whereby he myght have goten hym assistaunce and favoure agaynst oure said Sovereigne Lorde; and for the execucion of the same, sent oon John Taylour, his Servaunte, to have had delyveraunce of his said Sonne and Heire, for to have conveyed hym; the whiche Mayster John Tapton and Roger Harewell denyed the delyveraunce of the said Childe, and soo by Goddes grace his said false and untrue entent was lette and undoon.

The Kyng, remembryng over, that to side the neernesse of Blode, howe be nature he myght be kynde to his Brother; the tendre love also, whiche of youthe he bare unto hym, couthe have founden in his hert, uppon due submission, to have yet foryeven hym estsones, ne were, furst that his said Brother by his former dedes, and nowe by this conspiracye, sheweth hymself to be incorrigible, and in noo wyse reducible to that by bonde of nature, and of the grete benefices aforn reherced, he were moost soveraynly beholden of all Creature: Secondly, ne were the grete juparty of effusion of Christien blode, which most likkely shulde therof ensue: And thridenly and principally, the bond of his Conscience, wherby and by solempne Othe, he is bounden anenst God, uppon the peryll of everlastyng dampnacion, to provyde and defende, first the suertie of hymself and his moste Royall Issue, secondly, the tranquilite of Goddes Churche within this, his Royaulme, and after that, the wele publique, peas and tranquilite of all his Lordez, Noblemen, Comens and others of every degree and condicion, whiche all shulde necessarily stande in extreme jupartie, yf Justice and due punyshement of soo lothely offencez shulde be pardoned; in pernicious example to all mysdoers, theves, traytours, rebelles and all other suche as lightly wolde therby bee encoraged and enbolded to spare noo manner of wikkednesse.

Wherfore thof all [sic]11 the Kynges Highnesse be right sory to determyne hymself to the contrarie, yet consideryng that Justice is a vertue excellently pleasyng Almyghty God, wherby Reaulmes stande, Kynges and Pryncez reign and governe, all goode rule, polyce and publique wele is mayteigned; and that this vertue standeth not oonly in retribucion and rewarde for goode dedes, butt also in correccion and punysshement of evil doers, after the qualitees of theire mysdoyngs. For whiche premissez and causez the Kyng, by the avyse and assent of his Lordes Speretuell and Temporell, and by the Commons, in this present parliament assembled, and by the auctorite of the same, ordeyneth, enacteth and establith that the said George, Duke of Clarence, be convicte and atteyntit of Heigh Treason commyttet and doon agaynst the Kynges moost Royall persone; and that the same Duke, by the said auctorite, forfett from hym and his heyres for ever the Honoure, Estate, Dignite and name of Duke¹. And also that the same Duke, by the said auctorite, forfett from hym and his heyres for ever, all Castelles, Honoures, Maners, Landes, Tenements, Rents, Advousons, Hereditaments and Possessions that the same Duke nowe hath by eny of the Kynges Lettrez Patents to his owen use, or that any other persone nowe hath to the use of the same Duke by eny of the Kynges Letterez Patents, or that passed to hym fro the Kyng by the same: And that all Lettrez Patents made by the kyng to the said Duke bee from henseforthe utterly voyde and of noon effecte.

And that it be also ordeigned by the same auctorite that noo Castelles, Honoures, Maners, Landez, Tenementz, Rents, Advousons, Hereditaments or Possessions that the same duke nowe hath joyntly with other, or sole to hymself, to the use of eny other persone, be forfett, nor conteyned by or in this present Acte; but that by the said auctoritee, every other persone to whose use the said Duke is sole seised in eny Castelles, Honoures, Maners, Landez, Tenements, Rents, Advousons, Hereditaments and Possessions, otherwyse than by the Kyngs Lettres Patents, have power and auctorite by this present Acte lawefully to entre into theym, and theym to have and holde after the entent and trust that the said Duke nowe hath theryn. And also where the same Duke is joyntly seased with any other persone in any Castells, Maners, Landez, Tenementz, Rents, Hereditaments or Possessions to the use of eny other persone, otherwyse than by the Kyngs Lettrez Patents: that by the said auctorite, the said joynt feffez stonde and be feoffez to the same use and entent as they nowe arre and be; and that suche right, interest and title as the same Duke nowe hath with theym in the same premyssez, by the said auctorite, be in his cofeffez to the same entent as the same Duke nowe ys: Savyng to every of the Kynges Liege people, other than the said Duke and his Heyrez, and all other persone and persones that clayme or have eny tytell of interest in eny of the premyssez by the same Duke, suche right, tytle and interest as they owe or shulde have in eny of the premyssez, as if this Acte had never been made.

A cest Bille les Comunez sont assentuz.

Le Roy le voet.

Note 1. It is interesting that he forfeits the title of Duke rather than the usual attainted in the blood which may have debarred his children from inheriting the crown.