Baylis’ father, who came of a Gloucestershire family, established himself in London as a tobacconist and served twice as a common councilman for the City (on the first occasion at least, as a Whig). Baylis himself probably followed the same trade; he certainly followed his father’s politics. He was returned in 1708 for Thetford, where he was a ‘stranger’, with the support of the Duke of Grafton but principally by his own exertions, having reputedly spent some £3,000 among the voters. He was marked as a Whig in a list of the new Parliament, and his election was put down as a ‘gain’ by Lord Sunderland (Charles, Lord Spencer*). He was listed as having voted for the naturalization of the Palatines in 1709 and for the impeachment of Dr Sacheverell in 1710. Although the Norfolk Whigs wished him to put up for re-election at Thetford in 1710 he declined, and did not stand for Parliament again. He nevertheless played a prominent part in London politics, supporting Whig parliamentary candidates in several subsequent elections.
Baylis died on 21 Nov. 1748 and was buried in the church of St. John the Evangelist, Friday Street, alongside his father and two brothers. By a will dated only a week before his death his entire estate was bequeathed to ‘Mrs Mary Cash alias Carey, and Miss Caroline Carey her daughter, both now living with me’, to be divided equally between them.