The commentary doubles as a synopsis, and is reproduced below:

In the Warwickshire countryside, the backroom boys have come up with an idea which positively cuts out smoking. Their experiments have nothing to do with my lady nicotine, but to develop a new smokeless fuel.

In order to get into production, the engineers built a complicated-looking structure which is really quite simple. It's another backroom idea which really works. This pilot plant translates laboratory research into mass production.

The process uses small coal, which is plentiful, and it starts off with a good wash. It's then carried into the plant to be crushed and dried. If you blow heated air through fine-ground coal, it will behave like a liquid, as this laboratory demonstration shows. The coal will flow and absorb heat quickly, like water in a kettle. The scientists found that by carefully controlled heating, they could remove the smoky towers, and nothing more.

What worked in the laboratory can work on a larger scale, in the plant's fluidiser. In the time it takes to smoke a cigarette, the smoky, tar-laden vapours are removed. The carbonised coal leaves the fluidiser as a powder - char, they call it.

A little later it comes off the press as briquettes - hexagonal in shape, which when piled in the fireplace are less likely to roll off the fire than the round ones. No smoke, just a warm inviting glow, with a friendly flame. Perfect setting for a cup of char - in front of the char, so to speak.