Dave
I have a 'bible' with information of just about every RAF flying unit that has been in existance since 1912 giving their ancestry, formation and disbandment which is where I get this info from. It states that 192 Squadron were only allocated the QS designation for the period April to September 1939, but it was still allocated to them. I can give you any info you want from this bible which was bought for 50p from a library sale and is a great help for the research I'm currently doing for a still living bomber pilot from 44 Squadron whose just celebrated his 90th birthday.
Guy here's the info for you:
620 SQUADRON
TF Allocated for the period April to September 1939.
Formed 17th June 1943 at Chedburgh from 'C' Flight of 214 Squadron.
QS (6.43-9.46) Stirling III EF197 QS-Z, IV LJ566 QS-L; Halifax VII PP365 QS-H.
D4 (3.44-9.46) Stirling IV LJ566 D4-Y; Halifax VII NA458 D4-A.
Also used Stirling I W7465; Halifax III MZ682, IX RT769;
Dakota III KG344, IV KJ939; Horsa I LH403.
Disbanded 1st September 1946 at Aqir, Palestine, to become 113 Squadron.