Embarassing flat battery

After all the work that I've done to my truck I've been enjoying the last 3 weeks of just driving it and not having to worry about anything. In 3 weeks I've covered 1500 miles so a decent shakedown to unearth any other problems and it all been sweet. I drove to work 2 days ago and because it wasn't fully light had put my headlights on but by the time I got to work it was light and I had forgot to turn them off. I've probably become far too used and reliant to my vehicles beeping at me when getting out and leaving lights on so needless to say when it was time to go home I had a flat battery.

On checking the wiring diagram my truck doesn't have a lights on warning buzzer so on Monday a buzzer will be getting fitted!

My 1998 993 doesn't have one but my '02 and '08 1.3's do so I'd imagine they were introduced with the sloping front models (why isn't that named the Mark 2?)

Mines a 1998 1300, so Mk2. According to the wiring diagram for my year and model it doesn't have one. Maybe introduced at a later date?