The Trading Post was a British special effects and props firm founded in 1938 and still active as of 2016[update] with a focus on props hire. Bill King joined the company in 1960s, and at the company was hired to oversee visual effects work on the Doctor Who television stories The Moonbase, The Wheel in Space, The Invasion, The Krotons and The Seeds of Death, (DWMSE 43) of which the latter three stories The Trading Post had appeared in the credits.
Their sudden unavailability after Seeds caused tensions between Peter Bryant's production office and the BBC's Visual Effects Department. No longer able to rely on freelancer King, the VED were faced with much more work than they could handle, given the complex demands of both The Space Pirates and The War Games. This difficulty was solved by hiring John Wood, an ex-BBC designer who had gone freelance since his work on The Celestial Toymaker. (DWM 242)
The Trading Post also hired out its stock of props, a facility of which early Doctor Who designers occasionally availed themselves. It's known, for instance, that Raymond Cusick got the interior spaceship panels and other set dressing for The Rescue from The Trading Post (REF: The First Doctor Handbook). Additional scenery was hired from them for The Power of the Daleks, as was set dressing for the TARDIS control room in the first serial in 1963. Much later on, in 2013, the same pillar props used to dress the original TARDIS set were hired to be used for the docudrama An Adventure in Space and Time. (DWMSE 43)