I found these two postcards on eBay last week. Hand written on the back of both is "Went over these works while on holiday August 1936". So I think both are earlier images than the postcards that are reproduced in the Hayward and Atterbury book. Guessing at who the people might be - the middle woman to me looks like Eileen Prangnell pictured on page 45 of the Hayward and Atterbury book. The Potter I guess could be Burt Way who was the only male pottery at the factory in 1930 when Guy Sydenham started aged 14.
I'd be very grateful for any better ideas.