jks wrote:
I've just replaced the landing light with a 60w low power one.
The light is switched from downstairs and upstairs.
In one of the "off" settings the light flashes every 3 - 4 seconds, in the
other "off" setting it doesn't.
The cable between the switches is Y (240) B R G (earth).
The flashing occurs when the red and blue are connected to the light side of
the circuitry.

I assume it is capacitance between the cables that is causing the problem.
Apart from rewiring with separate cables is there any other solution.

John
It can be a problem with the cheaper bulbs. Try a more expensive one