Henry, a tip to save on fuses when you are troubleshooting a fault. Get a 21W indicator bulb and solder a couple of wires on to it with bare ends. Jam the ends into the fuse holder so that the bulb replaces the fuse.
When the short is there the bulb will glow at full brightness, when the short isn't there it will glow dimly or not at all depending on the load drawn.
This can save you a lot of money at Halfords who must sell the most expensive fuses in the country
