Around Feb 1643, John Hotham (age 33) was ready to switch to the Royalist side. He considered himself a better commander than Thomas Fairfax 3rd Lord Fairfax (age 31) and resented being under his command. In February or March 1643, Hotham started negotiating with the William Cavendish 1st Duke Newcastle upon Tyne (age 50), the Royalist commander in Yorkshire at Bridlington, supposedly about a prisoner exchange. In exchange for surrendering Hull and changing sides, Hotham demanded 20,000 pounds cash, the rank of viscount for his father and the rank of baron for himself.

In Apr 1643 John Hotham (age 33) joined his troops with the Parliamentarian forces in Lincolnshire. The bad behaviour of Hotham's troops, coupled with what appeared to be attempts by Hotham to co-opt the Parliamentarian officers, raised suspicions with then Colonel Oliver Cromwell (age 43) and John Hutchinson, the governor of Nottingham Castle. They denounced him to the Parliamentary Committee of Safety. In summer 1643 his arrest was ordered. He fled to Nottingham then attempted to travel to Hull. He was arrested with his father [his father] John Hotham 1st Baronet (age 53).

Diary of Isabella Twysden 1645. 01 Jan 1645. The first of Janua Mr Jo: hothum (age 35) was beheaded on tower hill [Map].