Diary of Philip Henry is in Stewart Books.
At the later end of the year 1648 I had leave given mee to goe to london to see my Father, & during my stay there at that time at Whitehal it was that I saw the Beheading of King Charles the first; He went by our door on Foot each day that hee was carry'd by water to Westminster, for hee took Barge at Gardenstayres where wee liv'd, & once hee spake to my Father & sayd Art thou alive yet!
On the day of his [King Charles I [aged 48]] execution, which was Tuesday, Jan. 30 [1649], I stood amongst the crowd in the street before Whitehal gate, where the scaffold was erected, and saw what was done, but was not so near as to hear any thing. The Blow I saw given, & can truly say with a sad heart; at the instant whereof, I remember wel, there was such a Grone by the Thousands then present, as I never heard before & desire I may never hear again. There was according to Order one Troop immediately marching from-wards Charing-cross to Westm' & another from-wards Westm' to charing-cross purposely to masker the people, & to disperse & scatter them, so that I had much adoe amongst the jrest to escape home without hurt.