UNIT commissionaire (Spearhead from Space)

A UNIT commissionaire guarded the vehicular entrance to the organisation's secret headquarters in Camden, London.

Liz Shaw and the UNIT chauffeur delivering her presented no problems. Their passes were in order, and the commissionaire let them through.

The Third Doctor, however, had not yet been issued credentials and arrived driving a stolen car. Before the commissionaire could even ask to see his documents, the Doctor berated the man and demanded to see Brigadier Lethbridge-Stewart at once. The commissionaire rung the Brigadier in the laboratory and was told to send the Doctor up right away. (TV: Spearhead from Space)

Behind the scenes
The actor originally hired was not providing what director Derek Martinus wanted. Out-going series producer Derrick Sherwin, who more-or-less fit the costume, stepped in and made an uncredited cameo appearance. (DOC: The UNIT Family)