Where in London can one purchase plutonium? In Covent Garden, at the Helios Homeopathy shop.

Dr Fiona Barclay, a chemist at RGB Research in west London, made this discovery. Her company specialises in selling collections of the periodic table elements (with the exception of those elements that are illegal or are so very short-lived - a few seconds or less - that they invite frustration). Some elements are easy to purchase: carbon, sulphur, iron. For others, one can turn to eBay, where arsenic, uranium (in the form of uranium-tipped missiles), and other elements of ill repute are commonly on offer.

But plutonium proved hard to find ... until Barclay turned to Google, which directed her to the Helios shop. She explains what happened next:

"I went to Covent Garden and went into the shop and said, 'Please, may I have some plutonium.' And the lady behind the counter said, 'I shall fetch the chemist.'

"The chemist was duly fetched, and I said, 'I'd really like a sample of plutonium.' She asked, 'And how strong would you like it, madam?'

"I had gone in there with the very good intention of asking what their original source was, because it's my understanding that, although they dilute everything until there's not even a molecule left, they do start off with one drop. But I got frazzled, and forgot to ask.

"The chemist gave me pillules, which very entertainingly have a 'best before' date of the 31st of March, 2013. And as I was leaving she pointed out that there was no plutonium in it.

British citizens are not limited to the one source. Freeman's Homeopathic Pharmacy offers "plutonium nitricum", also listed as "plutonium nit", for sale on its website. It also sells "Pan troglodytes (chimpanzee hair)", peach, peanut, pelican, "petrol and diesel fumes", "pig dust", "pig hair", and "placenta (human Welsh)".

Those are just nine of the 184 available items with names that begin with the letter "p". The firm offers homeopathic medicines from all the other letters of the alphabet, too. And yes, you can get uranium nit.

Helios, too, has a website. It offers four tablets of plutonium (236) nitricum for £4.06, but notes that "Helios remedies are without therapeutic indications".

Where can one go for therapeutic indications about medicinal plutonium? Provence, France.

In 2005, Dr Ramon Frendo of that city wrote one of the few existing monographs on the subject. Published in the Revue Belge d'Homoeopathie, it describes two patients whom Frendo treated with plutonium nit. One was a 59-year-old woman who had delusions and "had dreams about sharks", the other a 39-year-old who "hated her mother but could not leave her" and who "also dreams of sharks".

This followed by a year a related Frendo study called Guano, which appeared in the same journal, but which, perhaps inevitably, because of the sexiness of the plutonium paper, no longer gets its fair share of attention.

• Marc Abrahams is editor of the bimonthly Annals of Improbable Research and organiser of the Ig Nobel prize