Abandoned BSA in a ditch France 1940,rear wheel has been removed,hole in petrol tank could have been done with a pick to disable it?.

That looks indeed like a perfect square pickaxe hole. I have seen this quite a few times now on photo's and on original examples.

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I guess the bike in the back ground must be a WNG ?

If it's an Ariel (and I'm not convinced, with what appear to be flat rear mudguard stays and quite a tall gearbox), it can't be a War Office W/NG at that time. The only Ariels with the B.E.F. were either impressed civilian or possibly from a small contract of 100 x 500cc.

Like these perhaps? (But single port version...)

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