Well, I said the little Ford script wrenches seemed to fit Whitworth bolts. Maybe not... I tried a nice example and it did not fit the 5/16 BS and it was awful loose on the 1/4 BS nuts. Perhaps the one in my tool kit is worn and fit the 5/16 BS.
Here are some photos - purchased in the 80's when I could afford to buy stuff like this - I was married shortly after this and made fewer visits to the Snap-On truck.
7 Snap-On in "script" combi's 3/16 thru 7/16 BS. Used often except for the smaller sizes. In back on left is the Snappy box end marked in Whitworth 5/16 and 3/8. In back are three 1/2" wrenches converted to 5/16 BS obstruction wrenches. A necessity to reach the carb mount nuts and cylinder head bolts on the Royal Enfield.
To the right of the shiny Snap-Ons are four Superslim Made in England - very nice wrenches, two Snail brand wrenches - strong but clunky to use. Last on the right is a Vlchek 5/8 and 9/16 BS. Other wrenches in back are odds and ends but there's a BSA multi wrench that fits spokes.
A set of 12 Snap-On (script) 3/8 drive sockets crammed into a genuine Snappy tray, 4BA to 9/16 BS. The 5 piece 1/4 drive set is the later angular Snap-On lettering, 2 BA thru 3/8 BS.
Close-up of a 3/8 drive.
So not much of a collection but a well stocked working tool box drawer. Having these at hand made rebuilding the Enfield almost easy.
Al
The following may come under the heading of too much information:
I can't give speciifics on Whitworth sizes compared to inch. I know some of the larger bolts will fit inch tools nicely. The smaller common sizes like 1/4, 5/16, 3/8 and 7/16 will give you fits if you don't have a proper wrench. For example a 5/16 BS bolt will probably not take a 1/2" wrench, it might take a 13mm but chances are you will not get by with either size. The better made the inch or metric tool the least likely it is to fit a BS bolt.
The similarity of Whitworth to British Standard (BS) is that both are numbered for the size of the bolt thread (5/16 BS fits a 5/16 diameter thread bolt or nut). The difference is that Whitworth bolts have larger heads - hence a 1/4 Whitworth wrench can be used on a 5/16 British Standard bolt/nut.
Most of the threads on the Royal Enfield and my Triumph Cub are British Standard Cycle (also called CEI - Cycle Engineers Institute). This thread form fits British Standard wrench sizes. Most common BSC sizes use 26 TPI - 5/16 -26, 3/8-26 etc.
