WW2 RAF Standard Issue Watch Straps - Bund style

I know there is a ton of info (and air ministry specifications) for the CK2129 and then 6B/159 etc.
I was trying to find which watch Guy Gibson (Dam Busters) wore.

https://omegaforums.net/threads/guy...-617-squadron-which-watch-did-he-wear.121017/

It has been an interesting journey and I have ended up with a few pictures (I am not allowed to post them / permission issue) which makes me think 617 Squadron had some form of a standard issue RAF watch strap. It looks to be a Bund or Kitchener style black leather strap. Wider and more like some of the German straps for comfort and safety. Also if you loose a spring bar you would not loose the watch. Some interesting links below. Does anyone have more info or links to relevant old threads? Thanks
.

https://af0210strap.com/the-history-of-the-nato-watch-strap-part-2-the-nato-strap-during-wwii/

https://af0210strap.com/the-birth-o...tory-of-the-nato-strap-and-post-wwii-watches/

https://www.hodinkee.com/articles/editorial-case-for-bund-straps
.

Squadron Leader David Maltby DSO, DFC and Bar (killed in action September 1943 aged 23) was a right-hand man to Guy Gibson and one of the Dam buster pilots. He became the commanding officer of 617 squadron after the Dams raid when Guy Gibson took leave. He was killed on his 30th operation which puts the 170 of Guy Gibson in perspective.
A few shots below of the two comrades together. The close up shows the watch / watch strap worn by David Maltby and in another shot you can see Guy Gibson had a thick strap on his right wrist. Did the RAF issue a bund type strap to the Squadron or during training?