Hi Richard, I stole this image from an MG suppliers site, I hope they do not mind. Is this what you had in mind?

I can imagine this working and since the ‘W’ spring is easily dislodged, why it may have gone missing along with the rim clip.
I have just fitted a pair of LED dipping BPF bulbs, the output is amazing, I hope they will focus and give a good beam. I will have to have a night run, move the lamp bodies around to get them in place and then find a way to get a 7/16″ BSW spanner into the pedestal slot, both headlamp shells are loose?
Regards Jack