When George Orwell wrote what many still regard as the definitive guide to making a good cup of tea he laid out 11 basic principles, from warming the pot beforehand to stirring the leaves before pouring.

What he didn’t insist on was that the water, which Orwell said absolutely had to be at boiling point before being poured into the pot, should be boiled just the once.

But, on that point at least, it seems he was wrong. One of Britain’s leading tea experts has now said that the water used for making a cup of tea should never be boiled more than once.

William Gorman, chairman of the Tea and Infusions Association, warns that boiling the same water more than once removes the oxygen and nitrogen and results in a “dull” cuppa.

And, extraordinarily, Mr Gorman advocates something which - had they been invented - Orwell would surely have balked at; using a microwave to make tea.