My local Woolies, sorry F.W. Woolworth, tis Sunday after all, has those cheap 6 inch electronis digital calipers at half price, £12.50 instead of
25, at least mine did till I got there! Yours may have too (If you know where you can get them for less I don't want to know, just ignore this, I've had enough bad news this week with boilers and all. Cheers Andy