Throughout Britain, hundreds of sites where there were once petrol stations are now sitting empty, and seemingly clean. But in fact, the sites are unusable because of the leftover contaminants from the petrol and diesel.

Normally such contaminants would, in due course, be dealt with by micro-organisms that make their living out of cleaning up human beings’ mucky stuff. But the contaminants in this case are very small and hide away amongst the soil particles, making them almost unreachable by the micro-organisms.

Enter the heroes: Our old friends, the earthworms.

Put to work in the soil where the petrol and diesel contaminants lie, the earthworms chomp their way through it, and leave their excretions all over. The excretions include the now-revealed contaminants, and the way is cleared for the micro-organisms to do their part of the task.

During a 12-week period, a scientist in East Norfolk in England tested various samples of soil taken from a former petrol station. He divided it into various batches. Some were left as they were, some had earthworms added to them.

The samples containing the earthworms were around 80% cleaner than the samples left untouched at the end of the trial period. In other words, the contaminants in the samples the earthworms had been let loose on were now under the control of the micro-organisms who were completing their part of the process.

Worms can cope with surprisingly high levels of contaminants, apparently, and come out unscathed. With thousands of small petrol stations now closed, there is a huge amount of work for the earthworms of England to get their teeth into.

Mr Hickman says that further research is still needed, but there seems little doubt at this stage that the worms have a solid future in store.