The originals seem to last 20-30 years. That is OK with me.

The brake light pedal switch from a mid-1970s BMW 2002 is a good substitute for the plastic British pedal box switch.  You can order them for a reasonable price from Rock Auto.  Get the Airtex brand switch and it will come with the necessary jam nuts for setting the adjustment.

The price of the plastic switch varies wildly depending on where you buy it from.  I have seen the switch for as little as $4 and often as much as $12.   

Those plastic brake switches are absolute junk.  In Japan, they make a metal one that works better at the pedal box, but 3x the $.  Or you can retrofit an inline brake switch in the brake line.

They also get old and brittle and fall apart.

The car in question has an electric switch - they can fail or can become loose and stop working.  Either way it's time to delve up under the dashboard and look at the pedalbox.

Consider this an extension of Mur's post.

Early cars had a hydraulic switch on the front brake lines.  When you push the pedal the hydraulic switch would close and the lights would turn on.  If you don't find a mechanical switch on the pedal box, look for the hydraulic switch on the right, front brake pipes.  

An alternate test method for both switches is to unplug the wires from the switch and then hold the terminals on the disconnected wires together (metal to metal).  If the brake lights work with the wires touching, the switch is at fault.  If the lamps do not light with the bare wire terminals touching each other the problem is in the wiring or the lamps themselves.

Thanks--we'll give that a try!

Take a test lamp to the brake lamps switch, which is on the pedal box on your car. When the brake pedal is pushed, the switch is no longer depressed and this makes a connection. Check there with the ignition turned on. There should be power on one side of the switch at all times and then power on both sides when the pedal is depressed. If the switch fails it likely does not pass power through as it is supposed to. If one side is hot but the other does not get power when the pedal is depressed, connect the two wires momentarily and see if the brakes lamps light up.

If no power at the switch, carefully check all connections at the fuse box. If there is power there and the switch works as it should, then check the bulbs at the back. The switch is a wear item and has probably worn out. Easy to check, easy to change.

Okay, a new problem.  Noticed today when I pulled into the garage that there was no glow from my rear brake lights.  Had Hubby help me check, and I do have turn signals, but no brake lights.  Is there a quick and dirty way to sort this out?  Given that both lights are out and I have both turn signals, can I assume that it's not as likely to be the wiring in the boot?  In what order would you troubleshoot?