W211 Rotary Light Switch Malfunction At 'Auto'

[SmoothBall]

Hi,
Puzzling electrical issue (aren't they always?),

• Initially, I noticed over past few days that the boot lights were not turning on when boot lid was opened.
• Also noticed tonight that rear interior ceiling light was not illuminating when driver's door opened, though front ceiling light was illuminating.
  • The switch up by the rear view mirror to prevent these interior lights illuminating upon door opening was not depressed, i.e. front and rear lights should come on.
  • I guessed it was a fuse issue.
• Tonight, warning beeps and 'Switch off lights' in dashboard as I opened door with key out of ignition despite rotary, exterior light switch at 'Auto'.
  • It shouldn't complain at 'Auto'; it should just turn off the exterior, front and tail lights after I leave the car.
  • Exterior lights remained on until I set the switch to '0'.
• Found a website that,
  • indicated fuse 52 protects "Rotary light swich S1, Cluster, Glove Compartment". I checked it and it was fine, so I replaced it.
  • made no mention of what fuse protects interior ceiling or boot lights.
• Then a change in behaviour,
  • the rotary light switch was no longer warning me when I opened driver's door with key removed from ignition; appeared to be working as it should.
  • Rear interior ceiling light comes on when driver's door is opened, but only sometimes, not every time.
• Few minutes later, rotary light switch was back warning me to 'Switch off lights' even though it was set to 'Auto'.
• Boot lights never came on at any point.
• There is no malfunction reported in the dashboard, nor is there the "Battery convenience functions temporarily inactive".

So, what seemed like a simple fuse issue, now appears to be an intermittent problem affecting what you'd imagine are unrelated circuits.

Anyone know if there's a simple answer? Can anyone confirm what fuse 52 protects and what fuses control the boot lights and the interior ceiling lights/

Grateful if anyone could illuminate. (Geddit? Like what I did there? )

Tx,
Ken.