ron........I would not be so bold !! However, you have encapsulated the steps that were taken to convert the deH 60 M Moth into the deH 82 Tiger Moth that we know & love !!! It was indeed a stepwise process much of it done on the basis of "fag-packet calculations/suck it and see" methods...... It did happen remarkably quickly....!

Intertidal.... I am sorry I cannot help you with a unit or squadron.. I am sure there will be someone along shortly
who can fill in that blank. The photo is intriguing. Judging by the gent on the right's hat and the female on the steps on the left, I would think it may have been visiting a civilian airfield......

In the image of the Victoria you can see the platform at the base of the port wing rear interplane strut, its where a parachutist would stand until being pulled off when their chute deployed. Wiki says this 'Virginias continued to soldier on in support roles with the Parachute Test Flight at Henlow until December 1941'.

quick search gives the following:

1655 (Gipsy I) DH.60M toc as K1905 25.3.31 at Kenley.
To Practice Flight, Henlow 21.2.35 (or 21.2.33).
To Pilotless Aircraft Section, Henlow (2/5.38).
To 1 ASU 22.7.38.
Deld 17 ERFTS Barton 5.11.38.
Probably to 10 MU Hullavington 2.39.
To instructional airframe 1289M 18.2.39 and issued to 5 School of Technical Training, Locking.
Rtp 31.12.43

That did not take long....!!!!