Ignition barrel has two plugs coming out of it. I think (without going out to the garage to find the Haynes book) the smaller one just does the parking lights, and if you unplug it the parking lights will cease to function. You'll have to take the tank off, and you'll need to remember to plug them back in at MOT time.
Probably easier just to get into the habit of checking when you walk away from the bike
