Blenheim L3627 crash 1941.

Just a couple of query’s on this crash.

Blenheim N3627 based at RAF Oulton, Norfolk, with 139 squadron.

On 8th of August 1941 While practicing Formation flying over Oulton one engine, either caught fire or failed
It then crashed at North Barningham, and burst into flames, Farm workers tried to rescue crew, but were beating back by flames and exploding ammo.

Two crew were killed.
Sgt. (Pilot) John.Adrian.Gibbs, RAFVR. aged 20. Uk National. Service no: 1174298
Son of Eric N. Gibbs and Marjory E. Gibbs, of Westminster, London.
NORWICH CEMETERY, Norfolk Sec. 54. Grave 523.

Sgt. (Obs) James.Pierson.Shaw RAFVR (of Canada), aged 28. Uk National. Service no: 920449
NORWICH CEMETERY, Norfolk Sec. 54. Grave 524.

My questions.
A Blenheim usually has a crew of three, so did the third member bale out before the plane crashed or was he never on the plane as they were only practising this I find highly unlikely in 1941?

J. P. Shaw is on CWGC as a UK national but is said to be of Canada. And no mention of any family.
So did JP emigrate to Canada, and the war started before he was granted citizenship?

Thanks for any help.