For another person,this is what he wrote below.

I have this gun that was given to me, on top of barrel it has WJ Jeffery&co ltd 13 King street ST.James london . has other stamps like BV,BP,NP all with crowns . it has QS in a circle stamped trademark it has cordite 42-300 stamped also stamped is eather 333EXor 335EX can any one tell me what it is people have told me it is a big game rifle here are some pic hope they help.

http://s654.photobucket.com/albums/uu264/invisabill1958/wjjeffery/?start=0