He was christened on 21 September 1815 at Street Martin-in-the-Fields, Westminster with his parents being registered as Thomas and Sarah May. He was educated at Bedford School.
This derived from his career at the House of Commons. May began his parliamentary service in 1831, at the age of 16, as Assistant Librarian in the House of Commons Library. He was admitted to the Middle Temple on 20 June 1834 and called to the bar on 4 May 1838.
May married Johanna Laughton, of Fareham, on 27 August 1839.
May became examiner of petitions for private bills in 1846 and from 1847 to 1856 was Taxing Master for both Houses of Parliament. In 1856 he became Clerk Assistant of the House of Commons.
On 16 February 1871, he was appointed Clerk of the House of Commons by letters patent. In 1873, he was elected a bencher of the Middle Temple and awarded an honorary Doctorate of Civil Law by the University of Oxford in 1874.
In 1880, he was made a Reader of the Middle Temple and appointed to the Privy Council in 1884.
On 10 May 1886, shortly after his retirement as Clerk of the House of Commons, May was created "Baron Farnborough, of Farnborough, in the county of Southampton". He died on 17 May 1886 and left no heirs and so the barony became extinct, making it the second-shortest-lived peerage in British history, after the Barony of Leighton. Sir William McKay, who edited Erskine May"s private journal, has suggested that May was possibly an unacknowledged son or grandson of Thomas Erskine, 1st Baron Erskine.
1815 – Thomas Erskine May, Esq
1860 – Thomas Erskine May, Esq, Central Bank
1866 – Sir Thomas Erskine May, Knight Commander of the Order of the Bath
1874 – Sir Thomas Erskine May, Knight Commander of the Order of the Bath, Data Control Language
1884 – The Right Honorary Sir Thomas Erskine May, Knight Commander of the Order of the Bath, Data Control Language
1886 – The Right Honorary The Lord Farnborough, Knight Commander of the Order of the Bath, Personal Computer, Data Control Language.