That was a typo, I meant 539. It is not actually a long drop, just enough for mudguards on a steel frame with 700c wheels. I think the long drops are too long for my Raleigh Record Ace. So I suppose I have to go for Tiagra etc? My LBO will sell me two front ones rather than a set if I stick with the Tektros. My old steel frame isn't set up for inset retaining bolts, so the front brake fits on the rear with a coventional bolt. At the front I have to increase the hole size a bit at the back of the fork and then the insert hex bolt goes in.
Thanks for advice so far.