XP29: You're correct. I'm replacing my pedal and see the same situation. The original was a 1/4 x 28 but the replacement I bought is a 1/4 x 20 thread. The 1/4 refers to the diameter of the bolt shaft in inches and the second number is a U.S. measurement of threads per inch. This is such a common bolt & thread in the U.S. that I would "think" you can find the 1/4 x 20 nuts in the U.K.
mine are all 1/4-28. and are keps nuts.
Thanks guys, yes it would be handy if they included them! I was already ordering from Summit so got the pedal from there. I've seen them on US eBay that come with nuts, but they are getting on for $20 more!
Sorry, it's less than 20, found one cheaper, still $12 extra for nuts. Their shipping to UK is very expensive (this might be where I was getting the extra cost over Summit) $55 for eBay one with nuts
http://www.ebay.com/itm/Mopar-Gas-P...ash=item43d6cf478c:g:HtoAAOSwk5FUyFv1&vxp=mtr
$43 for Summit without nuts
http://www.summitracing.com/int/parts/mmp-ap25c
Didn't Imperial size fasteners originate from the UK? Maybe not in your town but would a larger city not have them?