[1] Withers was probably a Commissioner for taking subscriptions to land bank in 1696 and an Assistant of the Royal African Company from 1697 to 1698.
He was knighted by William III on 20 October 1699 when he was a member of the City delegation which congratulated the King on his return from the Continent.
He became Prime Warden of the Fishmonger's Company in 1700[2] At the first general election of 1701 Withers was returned as Member of Parliament for London.
[2] On the strength of being Mayor, he was elected again as MP for the City of London at a by-election on 16 December 1707, following the death of Sir Robert Clayton.
Also in 1708, he acquired a newly built house called Holcrofts, having a long avenue of elms in front, from Robert Limpany.