it's a Swiss made Pierce chronograph. I wanted something that a WW2 allied pilot might buy or be given by his family/friends, I was not sure of the date but a US Pierce collector has a 1945 advertisement showing this same model.
Here's some more views with a 1942 advertisement I found............
I now have about 15 WW2 watches aircraft clocks, they all work but it's not good for them to run without serviceing them. It would cost a fortune to have them all serviced, but I do wind them up every now and then just to see them run.
I wear my 1966 RAF Hamilton 6B-9101000 a lot (the one in the photo with the grey strap), that's the only watch I have had serviced.