Thomas Wheatley was born in Micklefield (nr. Leeds) in 1821. He was an apprentice with the Leeds & Selby Railway before working for the Midland, and Manchester Sheffield & Lincolnshire railways. He was then Locomotive Superintendent for the Southern Division of the L&NWR for 5 years. In 1845, Wheatley was convicted for manslaughter after driving an engine into the back of a mail train, but this does not appear to have hampered his professional career.
Then in 1867, he became the first Locomotive Superintendent for the entire North British Railway (NBR) network. Previously, this post had been split across divisions. Wheatley standardised and the modernised the varied NBR designs then in use. His standardised locomotives were noted for being more powerful than their precursors, and he was also responsible for introducing the first inside cylinder 4-4-0 locomotives to Britain. Wheatley also developed Cowlairs as the main NBR works.
Wheatley's position with the NBR was terminated October 1874. He leased the Wigtownshire Railway which he operated until his death on 13th March 1883.
Although a few of his designs survived into LNER ownership, his most famous locomotives, the inside cylinder 4-4-0s did not.