 Following the passing of the Reform Act in 1832 Manning was appointed as a revising barrister in which office he served the Borough of Newport in the Isle of Wight.He was appointed recorder of Sudbury in 1836, and recorder of Oxford and Banbury in November 1837, three offices which he held till his death.He was raised to the degree of a serjeant-at-law on 19 February 1840, received a patent of precedence in April 1845, and was made Queen's ancient sergeant in 1846.