GT;
Emergency Flashers, or "Four-Ways" as they were sometimes knows in the US, are a nice safety upgrade for a pre '67 (or so). I like the 140 style switches for this because the knobs pretty much match the others on the earlier models, they are simple to connect (only three wires!) because switches are completely self-contained in that they have their own Flasher Element, and they can replace the Ciggi Lighter for a sharp OE appearance...I've installed them on both 122 and 1800 models, like so:
...of course, you will loose the OE Lighter as a power outlet at that point, but as I recently wrote in response to another poster who wanted to now use his Lighter to power modern electronics, Lighters were not originally fused, and I have seen a vintage OE Lighter fail with serious secondary wiring damage...so improvements are well advised anyway!
My advice to is to locate and install one of these sharp 140 E-Flasher switches, replacing the Lighter with it, and also install a brand new Lighter/Power outlet, discretely on an added bracket under the dashboard, taking power from either terminal 30 (Battery Power) or 54 (Ignition Power, as before), but installing an in-line fuse (rated for wiring which supplies this new Lighter/Power outlet) in any case, for safety.
Suggested Reading:
http://www.sw-em.com/emergflash.htm
Cheers to "down unda" from Connecticut!