Thanks to the eagle-eyed reader who spotted a notice from HM Revenue and Customs stating that you don’t have to pay duty on fuel – if you make it yourself. If you fancy a spot of home brewing, you can produce up to 2,500 litres of biofuel a year without paying duties, submitting returns or declaring premises.

So how, as they might say at Practical Boat Owner, do you make your own biofuel? You need vegetable oil, methanol (200ml for every litre of oil) and potassium hydroxide or sodium hydroxide. Basically, you mix these and blend them, allow the mixture to settle and decant the top layer into another container, bubble wash it, settle and drain a few more times and, hey presto, you’ve got own-brand fuel.

Officially, this is a green light to set up a fuel factory in your garage. I’m just not sure how wise the saving would be. Would it be worth 40p a litre if you happen to live near an airport, drive a Jeep or work for the NHS?