Car boot sales is where I find most tools
Grandad dies & they sell a "box of spanners "
Look for ones that are black or dark brown
They will be made from very strong steel that untill th 80's could not be chromed easily
Also as there is no chrome , it can not flake off and make the tool loose.
Push bike stalls at swap meets are also good places to shop because untill very recient times there were a lot of Whitworth on push bikes.
2 minute thread leasson
Whitworth was an engineer in the steam age.
Back then threads were mostly cut on lathes or thread cutters so there were thousands of them but the UK finally decided to use Mr Whitworths threads.
However they were designed to work with the most common engineering metal at the time,,, grey cast iron so they had big heads proportional to the shaft size
During WWII when metal was scarce the heads were reduced as steel had bypassed cast iron.
Now to avoid every mechanic buying a complete new tool chest , they just used the next smaller head size, although it is actually a touch too small
When they did this the name changed from Whitworth to British Standard Whitworth and even the shorter British Standard
SO a tool can be marked W, WW , BSW or BS .
Because Whitworth was designed for use in cast iron it was found too coarse for steel so a new finner thread was introduced called British Standard Fine or BSF
the head sizes of BSF are the same as BSW or BS.
BSF replaced CEI ( Cycle engineers Institute ) or BSC (British Standard Cycle ) and they use the same head sizes as BSW / BSF as well.
The other confusing thread is British Association ( BA ) You will find these on Amal , Lucas , Smiths & Miller items
The bolts on your points are 4 BA.
BA works on standard wire gauges so it is backwards, the bigger the number the smaller the shaft
Some BSW tools will fit some BA and from memory BSA will only have 2BA, 3BA & 4BA at the worst .
So keep your eyes peeled for a set of Magneto spanners, they are usually pressed metal and on a keychain of some kind
The chart of head sizes is really handy till you get your head around it . not as complicated as it sounds.
Biggest size on an A10 is 1/2" but most will be 1/4 , 3/8 or 5/16
If you go for sockets look for 3/8 drive sockets which are slender so can get into those impossible places
A lot of aftermarket stuff, like muffler clamps will have Metric fasteners so I go to a boating supply shop & buy BSW or BSF marine grade stainless to replace the metric nuts & bolts.
Same story for mirrors & handle bar levers .
