see Poland Street 1 to 9 & 49 to 62 in London Addresses dataset
Thomas Gilbert Esq 50 Poland St ratebooks 1782-3 / perhaps Thomas Gilbert DNB 1720-1798. MP for Lichfield at this time but his town address was given in Royal Kalendar and similar publications through these years as Queen St, Westminster. A Thomas Gilbert junr, perhaps his son, was listed as a Clerk Extraordinary to the Privy Council in these years