didn't the race bikes prove to be quite successful?

Yes, they raced a number of seasons with relatively little improvement between seasons; they were basically road bike engines with special carburation and race pipes. They stood up to the competition extremely well and lasted a long time under hard race conditions. I managed to sit on one at Donington years ago and was astonished at the size of the bikes; they were little miniature gems.

some police bikes (called the "Interpol II" I seem to recollect) and in a very expensive road bike called the F1

There were a number of road bikes, both air and liquid cooled. The aircooled ones were first trialled by Durham police, and I got to wheelie one (yup, a full-faired Jam sandwich). I managed this 'cos my rugby club team coach was a RT Sergeant and he "loaned" me it for 10 minutes. When I got out of sight I whacked open the throttle and the front wheel just shot into the air. Marvelous - but not if you're a traffic cop. They didn't buy any; one of the delights of these early bikes was that when you went onto full left lock, the tension in the harness that ran under the tank caused the connector to pull off the ignition switch, which cut out the engine....

Virtually the same bike was produced in a small batch for public sale before they began production of the liquid cooled ones. There were again fully faired police versions and road versions; the Army, RAC and AA bought quite a few. Then there were the race reps - the second one was announced as the F1, which was basically their last gasp; the company tried to get the manufacturer of the race framed version to produce them in bulk, but the company collapsed.

To be honest, it wasn't the kit that was the problem - it was the same old warhorse, bad management. They didn't re-invest in the right machine tools and skimped on production, so the bikes just gradually got worse and worse. Finally, the management team were caught in some dodgy share dealing and the whole thing fell apart. Although there were rumours that the (then still in development) new Triumph company would buy them out, it never happened.

I'd love to know who owns the manufacturing rights to the engine, as it was the real heart of the bike; I have never forgotton just how tiny the bikes were (about the size of a 400cc), the massive torque of the engine, and the almost vibrationless operation; there was no red line on the tacho, and if you opened the throttle it was like there was an electric motor there instead of an IC engine. What a wonderful, wonderful machine.

One of the few remaining Mk1 owners... #00015