Recently the RH hand brake light on my Felicia failed so I replaced the bulb and it worked again. A couple of weeks later the same light failed and replacing the bulb again did not fix it. I couldn't see anything obviously wrong with the socket so I'm not sure where to look next. I wondered if anyone has had a similar experience and could help me?

i'm pretty certain both of the rear brake lights are wired in parallel from memory, so at least that proves power is reaching the back of the car, have you tried cleaning up the terminals in the bulb holder, they often get a bit green and crusty which prevents a proper connection

Could it be that you are talking about backlights, and not breaklights?
The two backlights have different fuses, LH side is 22 and RHS fuse 11.

If you really mean Right hand side stoplight, they should both be on fuse 14, so then I have nothing to offer beyond what Tom has provided.

Recently the RH hand brake light on my Felicia failed so I replaced the bulb and it worked again.

The hand brake has no lights at the back of the car, only a warning light at instrument cluster. So I guess you're talking about brake stop lights. In that case you should check the 6-pin connector that feeds the rear RH light unit for corrosion. A wire brush and WD-40 are your friends. Look for water leaks too. Careful when you insert the bulb.