Altberg do seem to be what I need. Wide or Extra wide i reckon will be a must though. Is there a decent model I should look into? Won't need them hard enough for crampons but decent ankle support is a must, more than what a fabric boot can offer.
Check out their web site -
http://www.altberg.co.uk/ They have quite a comprehensive range now. They do a number of different lasts, some of which are available in the 5 widths. They do boot fitting at the factory if you fancy a trip doon tae Yorkshire, and if you have particularly unusual feet they can even, for a price, make you your own unique last.
Bear in mind that a good fitting fabric foot will offer your ankle much better support than a poor fitting leather boot.