3 pin BC Lamp Holder?

[Bobster]

Hi all,
Might sound silly but what's the deal with BC lamp holders with 3 retaining pins? I came across these for the first time in a mates house in the Midlands. The house is only a few years old.
He's been walking round in the dark for ages as these lamps are pretty hard to come by! So I changed all his lamp holders to the standard BC type.

Just wondering, never seen them before or seen them again since!

If the answer is (and I suspect it is) to do with saving energy, then this has certainly been the case in this situation! :L

 

[Spudnik]

You are correct about energy saving.

They were originally a MEM design i think, so as to prevent the homeowner from using standard BC lamps.

Looks like he can now you have been in.