Johnny Winterbourne perhaps.
More information here including a list of staff members.
http://www.britishrecordshoparchive.org
George Foster was the leading light in the Jazz Society at UCL when I was there from 65 to 68. I didn't realise he worked at Dobell's
Thanks for that!
Surprised to see Roland Kirk omitted from the list of American musician visitors to Dobell's. He was said to be something of a permanent fixture there during seasons at Scott's, leaning on the counter and demanding to hear Fats Waller records.