Have a look here:
https://www.britishfasteners.com/Merchant...Affiliate=Basil
Whitworth is a Brit fastener system. Threads, sizes & bolt heads all different. Whitworth wrenches are sized by the bolt head dimensions. Us wrenches are sized by the bolt shank diameter. Both Whitworth & US threads are specified by threads per inch. Metric fasteners are specified by bolt diameter in MM & thread pitch from thread to thread in MM. Metric wrenches are sized by bolt head dimensions in MM.
King Dick is a Brit tool brand. There are a number of other brands of Whitworth sized tools.
It's kind of complicated. Some Brit cars have various combinations of different fasteners. Especially the older cars. The threads don't always interchange. Without going into a lot of detail, you can sometimes find a US or metric wrench that will fit Whitworth bolt heads, but not always. Taps & dies for these odd threads are a whole different ball of snakes.
I would suggest that you get the "odd" wrenches on an "as needed" basis, rather getting a whole set. Kind of inconvenient if you need a tool in a hurry, but the alternative is to buy a whole box full of various tool sets, many of which you will probably not need.
For example, I have a whole set of Whitworth sockets that I only use about three sizes of. Same with open end & box wrenches. If you go for sets, get the minimum available & add to it later if needed.
D