By 1694 he was the clerk of Richard Newman of Fifehead Magdalen, Dorset, whose niece Diana he married.
In 1724 he was appointed Clerk of the peace for Middlesex, a post he held for the rest of his life.
He did not stand at Bridport at the 1727 general election, but was then brought in as MP for Winchelsea at a by-election on 23 April 1728.
Henry Fielding referred to him as ‘Peter Pounce’, while Jonathan Swift wrote of him as ‘That rogue of genuine ministerial kind, Can half the peerage by his arts bewitch, Starve twenty lords to make one scoundrel rich’.
Alexander Pope also wrote several lines pertaining to him Walter died on 19 January 1746, and was said to be worth £300,000.