Since I got the car it kept blowing a fuse. It was intermittent with no particular pattern. I kept putting in fuses with larger and larger ratings. In hindsight not the wisest course of action. Got to 30 amps and it stopped blowing. So I assumed all was well.
While looking at something else my Dad noticed that a wire was touching the exhaust. Turns out this was the wire that goes to the transmission neutral safety & reverse light switch. So fixed the wire, tied it back properly, and thought all was well. Unfortunately that was not the case. The reverse lights were not working anymore (presumably for some time).
The neutral safety switch was broken, at least the reverse switch part of it. The switch was being shorted out each time the car was put in reverse. With the larger and larger fuses more power was going through which ended up melting the plastic inside the switch. Buying a replacement from the UK costs more than ordering from the US even when the tax and shipping is more than cost of the part :/ So for now will repair the existing switch. The unit was removed from the car, opened and repaired. Had to drill out the tabs that held it together as its not really supposed to be serviced. The contacts needed some solder on top to raise them back up to the correct level. After cleaning up the slider arm to remove the melted plastic. The part that holds the reverse switch roller needed new plastic adding to replace what had been melted away. With all fixed it was greased and glued back together. It clipped together quite firmly with a little glue it should hold fine. Woo! reverse light working again, no more blown fuses.