This applies not only to British cars but to any situation where you need to attach washers and a nut on a bolt but you can’t reach both ends of the blot because it is in a big box or at the end of the footbox in a MG Midget.
You put the bolt in the hole and then reach around to put the washers on before putting on the nut. Gravity does it’s thing and the washers fall off before you can get the nut started.
Solution: put a magnet or two on the top of the bolt hole. This magnetizes the whole bolt so you can put the washers on and they stay there!
Depending on the size and length of the bolt you will need small or big magnets. The stack of magnets on top of the bolt in the pictures are less than 1/4″ in diameter. Ten are stacked together in the picture. You can buy these magnets on Amazon, Ebay, Harbor Freight, or many other stores.
When you have finished, don’t forget to take the magnets off!