Reverse blows fuse

Hi one and all, just picked up a '91 Discovery TDI yesterday and spent more time in this excellent forum than I have in my beloved new toy! There is a good reason though, every time I push the gear lever over to reverse the fuse for the reverse light and stop light blows! I have resorted to unplugging the two wires coming out the reverse light switch so I have brake lights. The odd thing is, it blows before I have actually selected reverse I just have to push the gear lever over towards reverse and it pops. Any ideas as to what the fault could be or how to fix it would be greatly appreciated.

replace the reversing light switch.

The light normaly comes on when you start to push it over, rather than when you are actualy on reverse.