He was the second son of Sir Robert Tyrwhitt and Maud Tailboys, and was brought up at court, becoming an Esquire of the Body.
In 1544, when Master of the Horse for Queen Catherine, he served on a military campaign in France, responsible for the transport of ordnance.
He was a Member (MP) of the Parliament of England for Lincolnshire in 1545 and for Huntingdonshire in April 1554 and 1559.
He was also given custody of a house at Mortlake, Surrey, where he and his wife, a courtier herself, later took up residence.
[1] He is sometimes confused or conflated with a nephew, Robert Tyrwhitt, MP, particularly as both men married women named Elizabeth Oxenbridge.