rear lights playing up in a funny way....
started with the central check panel 'stop light' warning lamp coming on...thought was straight forward enough as drivers side stop light wasn't working...changed bulb....old one didn't look blown though...new bulb would not work either....then noted that PASSENGER side tail light connection seemed loose...sorted that...then lots of different combinations of things happened but I've ended up with...
1) ALL LIGHTS SWITCHED OFF - both rear brake lights work,
2) SWITCH MAIN LIGHTS ON - control panel shows that brake light malfunction and number plate light malfunction, also green light in dash that comes on when lights are on no longer lit, both brake lights work but passenger side tail light and drivers side number plate light not working [bulbs are ok], front lights / all fogs OK
recently had work done to repair worn / broken wires in the bundle that goes into bootlid..all well since...
...and I thought I just had to change a bulb!!
I'll second the suggestion to check the ground/earth connections.
Duff earths can cause all sorts of problems with lights. On a previous car, I had a sidelight that wouldn't light with the other one, but would flash away merily with the indicator! Turned out to be (another) blown lamp and a poor earth to the casing.
This is not necesarely an answer but may help.
I also had some times ago rear lamp problems, and find out that under the elastic rubber tub going from chases to boot lid the vires insulation where "broken" (for sure I had also fuses going out)I just simply insulat them with electrical tape and everything is OK since then.
When i was fixing a prob with my alarm i pulled off the right hand cover under the steering colum and found some fuses that didnt seem to be listed in the handbook, there were about 5 in total, 1 20A was blown, dont know what it did, replaced it and no difference! was it 1 of these?