@Seiji Welcome to OF, been a fan of your collection over on MWR for while now. That's a great reference - would be worth looking into fabricating a crown until the original hen's tooth version comes along.
You know they have the heritage flight watch with the huge crown. I wonder if that will work. I think it has the same crown extension.
They mostly show up in Knights Bridge auctions. Key point is to get the WW2 MOD ordered movement (e.g. May 1945); otherwise, it is just a pile of UK assembled scrap parts with no history.
Nice find (s) seiji...I have enjoyed your Mwr posts as well and this one is a beauty...just curious what are the production numbers on these?
I am working on a serial number project. It may take a while to develop an estimate of the production numbers. These watches are historically significant and will be highly treasured