This was a good informative documentary with an intriguing perspective presented with Ian Stewart's inimitable enthusiasm. The criticism that a bit more could have been said about the process of transforming sea life to oil over geological time was not unreasonable. Nor was it unreasonable to point out that the great London smog of 1952 had little to do with the lack of oil use. However it certainly was to do with the ubiquitous burning of coal in Victorian style home coal fires. It led to the banning of ordinary coal burning and the adoption of smokeless fuel zones using coke or coal "brickettes" and encouraged central heating using oil or gas. I remember well the massive coke mounds outside the Battersea Power station with all 4 chimneys belching away. That coke was of course the product from extracting coal gas from massive amounts of coal to fill hundreds of those large "gasometers" all over the country. However as I understand it most of the sulphur containing compounds that cause smog had been removed from that gas. Our electricity grid was not a major smog creator.