cast
John Steed	Patrick Macnee {regular}{New Avengers}{007}
Catherine Gale	Honor Blackman {regular}{007}{Dangerman}{Dr Who}{The Saint}
Basil, Lord Teale	Andre Morrell {regular}{The Professionals}{Dr Who}{The Saint}
Eric Van Doren	Philip Madoc {regular}{The Champions}{Dad's Army}{Dr Who}{Randall and Hopkirk}{The Saint}{The Sweeney}{UFO}{Jason King}
Lady Cynthia Bellamy-Barnett	Katy Greenwood
John James Wrightson	David Burke {The Champions}
Victor Gibbs	Geoffrey Alexander {Adam Adamant}
Edith Wrightson	Kitty Attwood {Adam Adamant}
Cooper	Ray Browne {regular}{007}{The Saint}
Clarence Arthur Wrightson	?
Jenny	?
Goliath	?
and Katie {regular}
Trade show attendee	Richard Pescud?
Trade show attendee	?
Trade show attendee	?
Trade show attendee	?
Trade show attendee	Phillip Webb?
Trade show attendee	?
Trade show attendee	?
Trade show attendee	?
Trade show attendee	?
man in newspaper photo	Richard Cuthbert?

crew
written by	Roger Marshall {The Professionals} {The Sweeney}
story editor	Richard Bates
theme by	Johnny Dankworth
designed by	Paul Bernard {Dr Who}
producer	John Bryce
directed by	Kim Mills
Floor Manager	Peter Bailey
Stage Manager	Nansi Davies
P.A.	Eileen Cornwell
an ABC Production

There are nine extras (maybe more?) in the trade show scene but they're very peripheral to the action and nearly impossible to get pictures of.

The Avengers

Series 3, 1963-4 - Episode 10