1942 Longbranch No.4 MK1* T .. original?

[Surpmil]

The general consensus is that the 71 pre-production snipers were built up on 1943 actions, in the 40L-56L range (or there abouts, don't have my book close by). This is not to say that a 1942 action could have been used. Did it have a scope serial # on the stock heel? As stated, the S51 stamp is the Holland and Holland mark, and was never used by Long Branch.
Here's a few pics of my 1943, one of 71. It was put back in fighting trim thanks to Brian Dick of BDL and Mr. Laidler, my thanks to both!

I see a "D" and a small Broad Arrow on the front pad. What's that all about? Very authentic looking "T" stamp as well, except that AFAWK no Canadian Ts got them except where applied retroactively on the individual initiative of armourers or civilian owners.

Is it possible some RSAF(E) made pads were sent over at the begining of the program at Long Branch and your rifle has them?