The rifle isn't mine; it was offered to me. Yes, 6 digits are too many; if I am not wrong, six digits are in the No. 4 Mk 2 S.N.
It seems that the rifle has gone into the arsenal in Canada: the fore stock is Long Branch.
What doesn't convince me, is not the S.N. on the butt socket, but the S.N. on the bolt and on the fore stock: I don't think Long Branch would have printed six digits.
Thanks. Giancarlo