Help ID an Enfield, possible 1917

[Mule]

Hey all, I have one that I can not figure out. I have a collection of them already, so I am familiar with a lot of the markings. BUT, his one is kicking my butt. It came to me from a friend's widow, I got it to help her afford his funeral.
It appears to be a 1917 Enfield. It has the Lithgow SHT LE III shield stamp on the right rear of the receiver, top left is stamped .303, next to that is the BNP crown stamp and below that is a MA VII stamp. Left rear below the safety arm is a MA/51 stamp and below that is stamped England.

My understanding was the M1917 Enfields were "American Enfields" in .30 cal.

Does anyone know this rifle?
Thanks
Greg
I'm having problems with getting uploads to work. I will see if I can figure it out and post a few more pics.