A.M. marked Surgical haversack

[enfield]

Newest addition to the collection: Surgical Haversack with Air Ministry markings. Slightly smaller than typical Shell Dressing bag or Airborne Surgical Haversack. Interior divided to three compartments with additional small pockets, two loops sewn under the flap. Faintly stenciled "SURGICAL HAVERSACK" on the flap, and clearly marked with manufacturers details and A.M.
It is an emergency pattern made from thin canvas without use of typical thick webbing.
Does anyone know anything more about this bag?
I will be gratefull for any information.