Let there be light

[SC David]

Thanks all.
Effectively after being nestled in the same socket for over 11 years my LKM didn't want to leave and I was concerned that its great resistance meant that I might have overlooked something holding it.

But... suitably encouraged (and emboldened ) by your answers I simply pulled - hard.
And it eventually let go.

Haha, that's the ticket. I thought there was something up with mine too, but, like everything else on my car it's just been in the same place for so many years that it was practically molded in there.