Lee Nowell wrote:

In the bathroom she has a number of spot lights (believed to by
240v) and when switch on, all lights come on as normal. When she
turns them off, one of the lights flashes on and off continually.
Has one of the incandescent or CFLs have been replaced with an LED? if
the cables to the light run parallel to other cables they could have
enough capacitance that lets the PSU inside the LED slowly "suck up"
enough power to give a brief flash, then rinse and repeat.

Another possibility, is if the lamps turn out to be 12V halogens with a
transformer, rather than 240V, a transformer might have gone faulty.