I only need a few of each variety and baulk at paying out for a kilo or more.

I did have foliar blight last year but all the spuds in storage appear fine, firm, no sign of rotting and a few pale sprouts starting in places.

Will they be secretly carrying blight? will I get a smaller yield than from 'proper' seed potatoes?

I always save some of my favourites for seed and they are good for several years. Some seem to lose vigour after five or six years and then I get some new ones, so you can save lots of money by saving your own.

Like you say make sure there is no sign of disease and give them a try. At least you will know if they do OK or not. We don't get much blight here, so I may just be lucky.

I've got quite a few varieties that aren't always available as seed potatoes, so try to make sure I've got my own. I like to grow just a few of a lot of different varieties and this is the easiest way to do it.

It's widely said that you shouldn't do it but friends of ours have used their own potatoes for years and don't seem to have any problems.
We always buy seed but then we do grow and use a lot of potatoes, so it makes sense.

We once got a trial sample of a new potato called ADORA from a seed company, and they were absolutely delicious. Easily the best I have ever tried. Unfortunately, they never appeared in the catalogue of any seed company again, so in this instance, I wish we had saved some instead of eating the lot!

Pity you didn't save a few of the Adora Elaine. I've ordered some Agria this year as the French chef chap - Raymond Blanc? - recommended them. I had trouble finding a supplier, so if they are good I'll definitely save some of those.

I got a very good crop of lovely good sized ones from four Rooster potatoes from the supermarket that had started sprouting. I'd say don't take any notice of what everyone else says - if you want to do something give it a try, it is the best way to find out. Things don't work as you want every time, but very often they do.