 He was tipped off by Lord Shaftesbury to withdraw a large sum of money from the Treasury before the Government suspended payment, and when Backwell was ruined because of the suspension, Duncombe took over his premises in Lombard Street at the sign of the Grasshopper.In 1680, Duncombe was appointed Cashier of excise at an annual salary of £600 p.a, holding the post until 1697 and Commissioner for the Mint, holding the post until 1686.He was six clerk in Chancery from 1682 to 1683.