On Cohen's coat there was not a stitch of thread, even to hold the buttons on. In shiny grey or black, it had welded seams and buttons, it came single-breasted with optional hood, or in a trench-coat version (with fly-front and welded belt and epaulettes). It rustled prodigiously. It was light, handy, foldable to pocket-handkerchief size, and he called it the Pakamac.
Being easily mistakable for a carrier bag, it suffers by comparison with classier rainwear. Which misses the point. Its real rival was never other macs, but another great British weather accessory, the umbrella. Convenient (less likely to be left on the train), thoroughly modern (this was the Age of Nylon), in its time the Pakamac was even acceptable wear for HMQ (though the Royal Warrant was not forthcoming). After its launch, there was a deluge of sales: 60,000 a week within 15 years.
Gradually, however, people realised that the only thing damper than walking in the rain unprotected was doing so encased in sealed polythene. Sales slowed to a drizzle, and production finally dried up completely in the Eighties. In 1988, however, the Pakamac reigned once again, when S Casket Ltd bought the brand name. As British as galoshes, it can still be found by the persistent, priced pounds 12.99, and is as impractical for you today as it's always been.