In a new book, an eminent English academic also claims that, at one stage, skulls were among the biggest exports from this country to England.

Dr Richard Sugg, a lecturer at Durham University, said so many skulls were imported into Britain they had plenty to sell onto the Germans, who were also into so-called corpse medicine.

Particularly prized were the skulls of the dead who had been deliberately left to rot on the battlefield. If left unburied, moss grew on them. The moss, when ground up with the skull, was said to improve the potion’s healing powers.

In many cases English troops also massacred villagers in nearby settlements. Dr Sugg said one of the reasons for this was to ensure they couldn’t bury the dead and thus interfere with the trade in moss-covered skulls. Skulls heavily covered in moss could be worth up to 11 shillings each to the seller, a small fortune in the 16th and 17th centuries.

Many were sold in chemist shops, especially in London. But the practice died out around the 1750s.

Initially the wealthy English used Egyptian mummies to create “medicines”. Later, however, Francis Bacon (1561-1626), the Elizabethan founder of modern science, noted that fresher, moss-covered skulls were better and that they could be acquired from “heaps of slain bodies” which lay unburied in Ireland. Bacon never set foot in Ireland, but got the information from his friend, the Earl of Essex, whose army butchered thousands of people here in the late 1590s.

The ground-up material could be drunk, or made into a paste to heal wounds. It was said to stop nose bleeds and also cure epilepsy and depression.

Dr Sugg’s research showed many of the present Queen of England’s ancestors took corpse medicines.

Charles II was particularly interested in using them and according to Sugg “more or less patented it”. The potions he created “became increasingly known as the king’s drops”.

Trade was so lucrative that the English imposed an import tax, called cranium humanum, of one shilling per skull.