John Barcroft, one of the Serjeants-at-Arms to Charles II in 1667, was assigned to bring the Duke of Buckgham to the Tower of London.
"The Sergeant-at-Arms was a personal attendant upon the King, especially charged with arresting those suspected of treason. Richard I had 24 with him on the Crusades. They were formed into a 20-strong Corps of Sergeants-at-Arms by King Edward I in 1278, as a mounted close escort. In 1399 King Richard II limited the corps to 30 Sergeants, and King Charles II had 16. The number was reduced to 8 in 1685 and since then it has gradually declined." http://en.wikipedia.org/wiki/Serjeant-at-Arms#Origins
Chart showing the number of references in each month of the diary’s entries.