2" Illuminating mortar

[Falcon]

Another one of my boot sale buys, an empty 2" Illuminationg mortar in quite good nick for £2. What do the markings mean? I know the main ones indicating what the round is, but on the opposite side there is:

12
H&W 3/68

OA

R.I.10/66

Stamped into the tail fins there is:

NO4-LOT523
BCB 12 66

And the tail cap:

2/51 S ORB 3

I would be grateful if anyone can tell me about the maker's marks or other markings.

[roller63]

Looks like four different makers for four individual parts. The only one I know is H&W which was Haley and weller, now part of the Pains Wessex group, PWD.

[Falcon]

I suppose Pains-Wessex (Manufacturer of flares etc.) would be the manufacturers of the pyrotechnic component. The other marking on the body would have presumably been the maker of the body itself.