UNIT commissionaire (Spearhead from Space)

This UNIT commissionaire guarded the vehicular entrance to the organisation's secret headquarters in Camden, London. (Spearhead from Space)

Liz Shaw and the UNIT chauffeur delivering her presented no problems. Their passes were in order, and the commissionaire let them pass. (Spearhead from Space)

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 berated the man and demanded to see Brigadier Lethbridge-Stewart. The commissionaire rung the Brigadier in the laboratory and was told to send the Doctor up right away. (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)