[2] He belonged to a group of poets called the Society of Friendship and was literary executive and adviser to one member: Katherine Philips.
[1] In Oxford, Cotterell collaborated with William Aylesbury in translating Davila's Storia delle guerre civile at the request of the King.
In March 1649, after the King's execution, Cotterell, along with his wife and elder daughter, accompanied Aylesbury and the Duke of Buckingham into exile in Antwerp.
By 1652 Cotterell had moved to The Hague as steward to Elizabeth Stuart, Queen of Bohemia, while completing a translation of La Calprenède's Cassandre.
After resigning his stewardship in September 1655, Cotterell was appointed an adviser to the Duke of Gloucester, under whom he fought in three campaigns in Flanders.
The pursuit of a young widow, Anne Owen, after the death of Frances his wife in 1657, led Cotterell to form a friendship with Katherine Philips, whose husband was the MP for Cardigan.