Parking lights come on of their own accord

[Del]

Came out of the house this morning, to see the Granada's parking lights on.
I know they weren't on when I came home last night.
Unlocked the car, the 'lights on' buzzer started, I checked the switch and it's off. Dips, beams & fogs all working fine. Turn switch back off, lights still on, buzzer still going.
Pulled fuses, lights off, buzzer on.
Checked fuseboxes, everything looks dry with no problems.
Will pull fuse for the buzzer circuit next, and may have to pull the bulbs & replace fuses (that fuse is for number plate light too, and I don't want a tug), but what's the probable cause?
First thought is a short in the switch?

[bortaf]

Do you meen the side lights (as in all 4 front and back) or parking lights (as in just the one side cos you left the indicator stalk to one side or tother) ?
TBH on a late granny the first thought is the fuse box, that's what killed most of them years ago but try relays ass well as fuses if unplugging the switch doesn't work, TBH i don't think the side lights are on a relay only dipped and main and not even sure if they have the idicator set parking lights ?

[Del]

Well, my first thought was side lights, because both sides were on. But then I noticed it was only the fronts, not the rears. So it looks like both parking lights are on!
Indicator stalk is off.
Bulbs out, fuses in - results in buzzer still going and number plate light on.
Bulbs in, fuses out - results in buzzer going and number plate light off.
Now I'm also thinking buzzer relay, as it will occasionally go off for a few seconds...
Headlight switch should just pull out, according to the manual, but can't get it to budge.