Lights left on warning

Now we are getting to that time of year where lights are sometimes needed during the day, has anyone fitted some means of warning that you have left your lights on when turning off the ignition?
I bought one from flea bay (admittedly I think it was only 99p but only just got round to trying to fit it) but it relies on the positive being switched i.e. power to headlight being switched on or off, on the hijet as I have found out its the -ve that is switched i.e. when testing at the contacts at the bulb they are always live and same at the fuse so couldnt figure out how to fit it.
It only has two wires, one to switched accessory power (tick got that) and one to the light circuit so it knows when its lit or not.
Wondered if amyone else had solved this?

Mine's had it? (it buggered up and I carefully removed it......)

My 1.3's have them, 1.0's didnt as far as I know. Maybe you can use one from a breaking 1.3?

Now theres an idea, mines a 993 so missed out. Any idea how easy it would be to remove and what it looks like?