Interior lights

[RattyCortina]

My van's rear interior light seems to have developed a weird fault. I recently noticed it was on when I was reversing onto the drive, I first thought it was coming on with the reversing lights. Had a play about this afternoon and discovered that with the switch in the 'off' position it comes on with the ignition, in the 'door' position it seems to behave normally. Also the front one will only work when switched on manually if the key is in the first position. (although that may be normal?)