In 1998 the Secretary of State for Defence appointed him as a trustee of the Royal Air force Museum; he retired in 2009. In February 1999, Hosker was appointed by the Paymaster General to conduct an Inquiry into the Customs and Excise aspects of the Simon de Danser drugs case"Botched drug raid had Minister's approval", The Herald Scotland, 12 February 1999.2000 Retrieved 8 October 2019. and in 2001 he conducted an inquiry on behalf of the Secretary of State for Work and Pensions into the handling of the C W Cheney & Sons Pension Fund by the Occupational Pensions Regulatory Authority."Darling appoints QC to Cheney inquiry", The Telegraph, 7 February 2001. Sir Gerald was appointed Public Inquiry commissioner in the Falkland Islands 1999-2000.
