OahuKaneohe,
Very nice rifle and great photos!
Thanks for posting them.
There are a couple of threads here on these Whitworth Express rifles if you get time to search for them.
This one indeed looks like one of the early examples which has sweated on front and rear sight and barrel band, as well as Birmingham proof marks.

I'm interested to know the action build date on your rifle.
It is located on the left side of the rear receiver ring, between the aperture sight mounting screw holes.

Thanks again for showing!