Sterling was educated at Dedham Grammar School. At age 16 on 8th July 1841 he went to Ipswich and commenced his articles under Mr Chas Steward and was admitted a Solicitor in 1847. He went into partnership with George Josselyn in 1848 but the partnership was dissolved in 1855 whereupon he practised on his own. He had moved the practice to 32 Museum St by 1868 and his trade directory entry for 1869 read 'Solicitor, Clerk to Justices for Stanford Division, Commissioner for administering oaths in Chancery and special agent for London and Provincial Assurance Society.' In 1870 he took on two clerks, his nephew, Alfred Townshend Cobbold and Harry Nathaniel Catchpole. The latter died a year later. After many years practising on his own, in 1888 he took Alfred Townshend Cobbold and Charles Ward into partnership and the practice became Westhorp, Cobbold & Ward, still at 32 Museum St. Ipswich.