Strobing downlighter

[Pip]

I know nothing about this install but a phone call from a friends daughter in studet rented house in London.
Downlights in her bedroom and switched off but one light strobes at full brightness.
Whats going on?

 

[DT1991]

Have connections and voltages verified.

With switch on and off.


Edit - remember some time back a batch of gu10 would be partially lit even with no voltage?? No explanation just changed lamp.and job done

 

[Strima]

Induced voltage from other circuits, voltage rises to a point where the driver can fire up the LED which discharges the driver capacitor for the cycle to start over again.

 

[Midwest]

Or perhaps problem being caused by dimmer switch, if fitted.