In most UK fish and chip shops they sell saveloy sausages. Is it true that these are made from horse meat?

No. According to a few sources, they are made from pork.

http://www.theanswerbank.co.uk/Food-and-Drink/Question322175.html

https://en.wikipedia.org/wiki/Saveloy

http://www.thefreedictionary.com/saveloy

I've often wondered what a saveloy was. Wikipedia may say they sell them in most English fish and chip shops, but they are unknown in my locality, and I've never seen them anywhere else either (Lancashire, Yorkshire, Forest of Dean in the main for chippie visiting). Chip shop sausages to me are thick brown things in two lengths: standard and jumbo. Either length can be battered as well, but in some parts you get odd looks for asking. It's probably a London thing, where London reckons it's England. (I've never yet been in a London chippie. I'll have to look next time I'm there.) It could be that the whole of the rest of the country sells saveloys and I've just been to the places that don't.....