I realised I had brainwashed my sons when one bought a ‘cold cure’, saw my cynical expression and said: “OK Dad, I cannot quote a double blind clinical trial but I find them helpful.”

With all the research into vaccines and treatments for Covid-19 there seem to be more trials than at the Old Bailey. But where did the idea of a clinical trial came from?

In 1753, the navy had a problem. In Lord Anson’s circumnavigation of the world in 1748 out of 1,900 men, 1,400 died of scurvy.

This was at a time when most doctors did not believe in evidence or experiments. They stuck with the remedies they had been taught.

James Lind, a Scottish naval surgeon based in Plymouth, realised that all the descriptions of scurvy were either written by seamen who were not doctors or by doctors who had never been to sea.

He first went to sea in 1730 and had been on a ten-week voyage when 80 out of 350 sailors went down with scurvy.

He was blunt and to the point. “Before the subject could be set in clear and proper light, it was necessary to remove a great deal of rubbish.”

Scurvy, he claimed, was killing more men in the British fleets than the Spanish and French put together.

As any modern scientist would do, James Lind searched through all the reports of the disease. Today, this would be called a systematic review.

We now know that scurvy is caused through a lack of vitamin C but, in James Lind’s day there were hundreds of theories.

He divided 12 sailors into six groups, some were given sulphuric acid, some vinegar, some sea water, some a spicy paste and some two oranges.

After six days both the sailors receiving oranges had improved and one was fit for duty. All the others were still unwell with scurvy.

The year after James Lind had published his findings the navy’s ‘Sick and Hurt Board’ rejected a proposal to provide sailors with supplies of fruit juice. It was another 42 years before the navy accepted Lind’s advice.

In fairness to the Sick and Hurt Board, Lind’s paper was one of many. They were not helped by Lind’s first suggestion that they should mix fresh fruit juice with boiling water. We now know that boiling water destroys vitamin C. But they were impressed by his idea of a trial and ordered trials on treatments for fevers.

Gradually naval officers took the advice on board, literally. In 1794, Rear Admiral Gardiner issued lemon juice to all the sailors on a voyage to India and there was no scurvy. The admiralty then ordered lemon juice to be issued to the entire fleet.

Unfortunately, there were not enough lemons and so they were used for treatment rather than prevention. By 1800 there was enough lemon juice to be issued to all sailors.

Being able to prevent scurvy gave the Royal Navy a massive advantage. They could now blockade ports or chase enemy vessels for months.

By 1850 the Americans, realising that the Royal Navy added lemon juice to daily grog, thought they were insulting us by calling the Brits lime-juicer, shortened to Limey.

The words lemons and limes were interchangeable. So a word meant to insult us Brits is based on the fact that we were ahead of the field.

It was not until 1912 that vitamin C was discovered and not isolated until 1928.

Lind’s clinical trial would not be accepted today. We could not prove how effective a coronavirus vaccine or treatment might be from a trial of 12 patients split into groups of two.

But he pioneered the idea. If we really want to know how to treat coronavirus or any other disease we need a systematic review of the literature followed by a controlled clinical trial.

I am sorry if my kids were fed up with my banging on about controlled trials but don’t blame me; blame James Lind.