No brake light when ignition off

Suddenly I’ve noticed that the right side brake light on my 1988 Vanden Plas no longer works when the ignition is off. At first I thought the bulb was out, but I found that it worked when I turn the ignition on. Are the brake lights supposed to work with the ignition off? The left side does. What should I check as the problem?
My car’s steering wheel is on the left side.

I’m just wondering why the brake light would illuminate when the ignition is off? Are you saying the opposite side works with the ign off?

Yes, the opposite side works with the ignition off. Should it not?

Can’t see any reason why it should, I’m fairly certain neither my ‘88 or ‘92 XJ40 did that, there are current owners on here that should be able to confirm which is correct.

Well, I just checked and the right side is now working with the ignition off. Apparently that’s the way they’re supposed to work. I don’t know why it Stopped working. I’ll keep an eye on it.

How bizzare, all 3 of mine come on, never thought they were not supposed to but they do!

I think the brake lights are supposed to also work with the ignition off. Since my original post, mysteriously, the lights are now working with the ignition off.