Pulsing landing lights?
Observed from West London, UK around 17:25z on Sunday 25th January:
An aircraft appears low from the south east, from approx. direction of LGW, flying north west and climbing, eventually turning north and continuing overhead London. Unknown type, but from speed and lights arrangement could be narrowbody commercial (but not Airbus, as no double flashing strobes).
All the time though, its landing lights (at least two, could be more) are pulsing, at approximately 1 cycle per second, from full on to practically off and back again.
I've never observed this before. Anyone any ideas as to what/why?