Hello Michael. Sorry I've been a little slow to respond, but tonight I had a look at the three rifles for the markings on either side of the bolt way on the rear of the body. (None have a receiver side wall T). As follows:

1941 0C3XX LHS bolt way - nothing. RHS bolt way - Upside down stamped 'T' within a circle. US ordnance flaming bomb.

1942 12C93XX LHS bolt way - nothing. RHS bolt way - stamped letter 'P'.

1942 14C02XX LHS bolt way - nothing. RHS bolt way - either a figure '8' or possibly a US ordnance flaming bomb. Poorly stamped.
- just 'round the corner' on very top edge of RHS butt socket is an Enfield examiner's stamp. Crown/7?/E. I really can't say
what the letter is after the '7', & am not sure about the 'E' but think that is most likely. Again, poorly stamped.