hoping someone may be able to shed some light on this.
last week my dad pointed out to me that i had a brake light out, i got a bulb and changed it, checked both brake lights worked and thought that was job done. But now after driving at night last night ive noticed that the light i changed now only does the brake light, whereas the other side is lit up red at night and also a brake light. im presuming ive made a rookie error, but ill freely admit im useless at this sort of thing.
many thanks

These require dual filament bulbs known as
5/21W
Brake/tail. Designed 50 years ago.

They have 2 Connectors on the base.

Did u fit one of those ?

I can’t find the packaging for the one I put in, but if I go and pick up the ones in the photo, are they the correct ones? Thankyou for your reply

yes, those are the ones

Thankyou, just been to Halfords and picked some up. Both working now. I’ve attached a photo of the ones I bought originally, neither bulb worked as both the tail and brake light, it was either one of the other which I found strange. Either way, sorted now. Thanks for your help