Help! Ignition Stuck On

[Renton500]

Hi, My 91 325i Tourer has a strange problem, can anyone help?

A Friend walking up my drive pointed out that my ignition lights were on on my dashboard. I grabbed the keys and went to investigate. I turned the key a few times and it didn't make any difference. I started the car and the lights went out as normal, but then I couldn't turn the engine off!!

I took the car for a drive round to someone else's house and when I got there the engine and ignition turned off ok. I went inside the house for 15 mins, came back out to the car and sure enough the ignition lights were all on again. I started the car and couldn't turn it off again. As it was dark, there wasn't a lot i could do, so i drove the car back home and it's currently sat on the drive with the battery disconnected.

Yesterday I tried disconnecting the ignition switch while the ignition lights were on, but this didn't seem to make any difference.

Any suggestions would be much appreciated.