Big thank you to everyone posting information. It was indeed an 8 speed uniglide cassette. I know some of you will be saying "I told you so" , but there were so many opinions, I didnt know which ones were right!
(Also, big thanks to the nice young man at Halfords who let me use their chain whip tools for nothing)
If anyone is interested, heres the pictures of the disassembled cassette: https://plus.google.com/photos/100036427370762655243/albums/5751020505943983329
So, the question is now, what sprockets do I put on??
Currently have 13,14,15,16,17,18,19,23
My two options are:
13,14,15,17,19,21,23,25 - so i would need 23 & 25
13,14,16,19,21,23,25,28 - so I would need 23,25 & 28
Would love to get a 28T on there although not sure if the mech will take it.
If anyone has these sprockets that they'd like to sell - preferably uniglide, please PM me.