Glad you didn't do what I did. Left it in drive, after turning ignition off. Sat in the car while waiting for the missus. Then tried to start the car and nothing. After a bit of blind panicking realised I had left it in Drive. You live and learn.

Might be worth keeping some graphite lock lube in the car for emergencies.

Thank you everybody. I can't find who had the TRUTH, but it's definitely the little black rectangular piece that drops out if you left the works out of the key. I bought a new rubber fitting to replace the old buttons and the piece fell out in the process - it's under the circuit board at the key end. Luckily I found it when clearing up and took it for some kind of spacer. I've just replaced it and everything works. (or will do until the WD40 gums it all up.