He seems to have had an unusual depth and breadth of legal experience – articled when still young in an attorneys' office in Alnwick, Northumberland, said to be the nicest place in Britain, and was admitted a solicitor in 1830, and practised for twelve years as a member of the firm of Meggison, Pringle, & Manisty in the Kings Road, Chelsea. He then studied at Gray's Inn, and became a barrister in 1845, and QC in 1857, appearing mainly in mercantile and circuit cases. In 1876, he was made a judge, and was knighted.

johnbabbacombelee.com/whos-who/

(Manisty presided over the trial and conviction of John Lee, the Babbacombe murderer known as 'The Man They Could Not Hang').

An eloquent tribute to the memory of the Judge was paid in the Lord Chief Justice's court: The Attorney General said that "during his 30 years on the Northern Circuit he never made an enemy or lost a friend", and that on the bench "he displayed a patient industry, universal courtesy, and untiring consideration". Lord Coleridge spoke of him as "a good judge, a good lawyer, and a good man". He concluded by noting the great judicial qualities of Sir Henry; "his wide learning, his keen sense of duty, his warm and generous nature, his unswerving and incorruptible integrity".