My RP has a pair of Lucas headlamps which have been with the car since I got it in the 1980s. The lighty bits are Marchal with dip/main ba21 bulbs and festoon pilot light. I have no idea where they came from but they work OK. I think the rims are converters but also date back to when I got the car. The strange thing is that the nearside shell has a grommet in the end which is absent on the offside unit. The hole in the end of the shell is properly spun as though it should have a little lens in it to show that the sidelight is on but I'm only surmising. I'm not sure it would be visible from the driver's seat.

Anyone any ideas?

Location: Gard, France 30960

I believe that this hole is to take the bolt for the dipping solenoid mechanism where the nearside dipped and the offside lamp went out!. My RN is identical in having a hole in the rear of the bowl.

Location: Near M1 Motorway Jtn 28

Now that makes sense! Good call.

Location: Gard, France 30960

Good evening Reckless. From your photograph I think that you have Lucas L131 headlamps which were not introduced until the introduction of the Ruby in 1934. The give away is the more pointed (bullet) shape whereas the RP should be fitted with the LB130 which has a more rounded back.
Brian is quite right, the hole in the back of the n/s shell is to take a shouldered countersunk screw which supports the solenoid dipping mechanism.
I am intrigued that Brian's RN is so fitted as one of the strengths of the RN was the fitting of Lucas 35/32 headlamps with the 'Lucas Graves' double filament bulbs which as Dave Mann is on record as saying elsewhere is infinitely superior to the 'n/s on o/s off' dipping arrangement of the Ruby.
Regards
Stuart

Location: Staffordshire - the creative county

Stuart, my RN is fitted with double filament dipping bulbs but they are in much more modern reflectors. Perhaps it was once fitted with solenoid dipping ones but the car has obviously been messed with over the years.

Location: Near M1 Motorway Jtn 28