The commentary doubles as a synopsis, and is reproduced here in full:

To win every ton of coal, two to six hundredweight of dirt have to be mined as well. What happens to this dirt, for it doesn't all go into the coal ration?

In fact, every effort is made to keep it out. In the old days, it was least trouble to pile it up just outside the colliery, until great ugly heaps mired the countryside and polluted its atmosphere. But at some of the most up-to-date mines, including the modernised Coventry Colliery, you will see no pit-tips. For as soon as the dirt is washed from the coal, it's carried back underground and is stowed pneumatically where it came from.

This is one of the methods we expect to use more widely in the future. But in some places, the dirt is already being put to good use on the surface. At Blyth in Northumberland, where for years the sea has been eating away the coastline, the dirt and stone rubble from the Cambois Colliery is being dumped on the shore to make a seawall. And in the estuary of the River Blyth, the rubble from the Bates pit is being used to reclaim the land washed away from the banks.

As for the great tips already in existence, in the Rhondda Valley they're being levelled to make children's playgrounds. At Cowdenbeath in Fifeshire, Coal Board scientists, with the help of Edinburgh University Forestry Department are experimenting with the idea of turning coal tips into forests. Trees are chosen that suit the type of soil on the beath. Already, about a thousand of these have been planted. If they flourish, the scheme will go ahead. Instead of bleak tips, the coal areas of the country will have wooded hills that will bring back their old rural beauty - and provide a regular supply of timber. On the pit waste of yesterday, will grow the pit props of tomorrow.