Through his mother, who married as her second husband Sir Robert Savile, Thymbleby was connected with the local families of Hussey, Savile, Tailor and Monson. Succeeding Robert Monson as recorder of Lincoln, and obtaining the deputy recordership of Boston,
Thymbleby had a considerable conveyancing practice in Lincolnshire, for his name appears as attorney in a number of final concords for land there. In 1579 he was involved in a dispute with a servant of the Earl of Leicester over the lease of the parsonage of Belton in Axholme, which was owned by the city; he promised to ‘yield up all the interest that he may claim’. During the years 1584-7 he was involved in the disputes about the mayoralty of the city, which were sufficiently serious for the Privy Council to intervene. His labours were rewarded in January 1587 by a grant from the common council of a hogshead of wine. Thymbleby died before the disputes ended, during an outbreak of plague in Lincoln. Because of the infection no entries were made in the city minute book 20 May-22 Aug. 1587, and the first entry after the interval records Thymbleby’s death. He died intestate, as his wife had done the previous April, and administration was granted to William Thymbleby, son of his elder brother Richard. Thymbleby was apparently buried in his parish church of St. Swithin, for, though neither register nor transcripts survive for this period, Gervase Holles recorded his memorial window there.