Thanks for all the info gents, I must say that Fernandos link to Richard Steins website was a real eye opener!
I've managed to pull the blade form the handle- not easy as the thing is bloody sharp! I hope the pics shed a little more light on this dagger. The peg hole in the handle dosn't line up with the hole in the tang, so I guess this is a composite piece, that said, it took a lot of force to remove the blade, I had to remove a lot of rust- me thinks there is some age here and not a modern made in China job. What ever it be, it feels good in the hand and would I'm sure have performed well in action. I can see no marks on the tang-but then again, I hardly know what I'm looking for
Out of interest, the seller has got the scabbard that came with the dagger when he purchased it. I will get it at easter ( he forgot to bring it to the sale) when we meet again at the next antiques fair. Many thanks for all comments and opinions.