The top section is Air ministry marked with a faint code which I think reads: 1116239/39 / C12.
In good condition, it has the serviceman's number written on the underside of the flap. One of the small side straps is missing off one of the shoulder straps.
 
The bottom part is made by Michael Wright & Sons Ltd and dated 1941. Also Air Ministry stamped.
Again this has been marked with a service number in a couple of places and it has a patch of red paint at the back of the pack. This isn't seen when the pack is put together / worn.
 
Becoming increasingly hard to find.
 
Weight 1.02kg.