The beacon :
1966-67 Corgi Batmobile gloss black - silver beacon cage.
1967-72 Corgi Batmobile gloss black - silver beacon cage (1967-1970), gold beacon cage (1970-1972)
1972 Corgi Batmobile red tyred - Beacon cage was gold on every model from now except one.
Corgi Batmobile - Curiously, only the purple glass retained
the silver beacon cage (?).
Batboat 1967-76 Tin fin version - beacon cage (early versions looked like a dark silver, later versions from 1970 it was gold).
Batboat 1976-81 Orange fin version - no beacon cage at all.
The majority of purple glass i've seen have also had silver beacons, but i suppose Corgi could have put on gold ones on a few, either that or someone has changed the beacon cage, which as you know is very easy to do on any model. Every purple glass i saw in the shops all had silver beacons. I've seen early 66 models with no towhook being presented before with gold beacons, whilst the model is still mint. It's all down to an owners preference really, as i have put a gold beacon on a 67 model before, just through personal choice!!! I would say 99.9% of the time the purple came with a silver beacon, theres always a possibilty it did come with a gold beacon to start with, It could simply be that the owner changed the beacon too.
They probably wouldn't be aware that certain models came with certain beacons.
A lot of the batmobiles had what were called longer red lights or were to big to fit properly into the hole, which caused it to protrude out of the top, which in turn didn't hold the beacon cage down very well!! So consequently when the box was moved in the shop for example, these sometimes fell off and lost forever. This was very common on the whizzwheel versions, and rarely happened on the red hub versions.
Sometimes too, the red light piece was too thin and didn't stick in very well and fitted very loosely!! I've had a couple of these too before, and i had to glue the red light into place :