Should London make itself the natural home for cannabis-related stock-market floats? The case that it should is simple: for the money. The case that it shouldnâ€™t is much hazier, especially if weâ€™re moving towards formal legalisation of the weed, and away from the present typically British situation, where itâ€™s officially illegal but in practice no one much cares.
Aside from firms growing plants that make people high, thereâ€™s a whole other breed of companies seeking capital that are exploring medical marijuana.
The products they make are usually an oil which people might take as a shot with their morning coffee, or as a tablet before bedtime.
These â€śwellnessâ€ť products are said to be good for everything from anxiety, to sleep disorders to perhaps really serious illnesses such as Parkinsonâ€™s.
The science for this is thin at the moment but itâ€™s early days.
The problem comes with the grey area that exists around the Proceeds of Crime Act.
If youâ€™re making an anti-acne cream based on marijuana that has no recreational properties, the risk is theoretical, but serious enough to prevent anyone from investing. At the moment the banking advisers, Nomads and fund managers needed for a successful float would shy away from a marijuana-related IPO.
Compliance departments are jumpy enough at the best of times; this sort of stuff is a no-no as far as they are concerned.
Which brings us to EXMceuticals, a Canadian firm which has already floated in Vancouver and Frankfurt with a value of about ÂŁ30 million, but would like its main listing to be here.
EXM makes products using CBD,Â Cannabidiol, from which THC, Tetrahydrocannabinol, the woozy stuff, has been removed.
What does it do with the leftover THC? It has a massive party. (Not really).
Chairman Jonathan Summers, a former banker who admits that a year ago he hadnâ€™t even heard of CBD, thinks London is missing a trick here. Cannabis oil is legal in Europe already and America might soon relax its laws so it can be used as a food supplement.
Bank of America thinks the market could be worth ÂŁ30 billion by 2032.
â€śA lot of people are very excited by this but to grow the market we need CBD to be available,â€ť says Summers.
â€śWeâ€™d like to move our primary listing here to access the capital in London. But we need the law to be clarified.â€ť
Part of the concern from regulators must be that Londonâ€™s reputation ends up tarnished.Â
If it opens its doors to cannabis floats from firms making false promises of miracle cures for all manner of ailments, all that will happen is that investors get burnt.
It could be Dutch tulip mania all over again.
â€śThatâ€™s obviously a fear that certain people have,â€ť Summers tells me. â€śBut thereâ€™s also a massive degree of curiosity here. London has traditionally been a place where innovation wins.â€ť
EXM isnâ€™t quite ready for a London float, but thinks it could be by the first quarter of next year.
The case of Billy Caldwell shows authorities can move quickly when they want to. The 13-year-old epileptic boy had life-threatening seizures after he was refused cannabis oil on the orders of the Home Office drug enforcement team.
Home Secretary Sajid Javid got involved and sense prevailed.
Perhaps the stock market regulators could show similar enlightenment.
Investment banking is a strange old business, and no one practises it more strangely than Deutsche Bank.Â
Only within this curious world would paying out â‚¬52 million to your top executives as you turf 18,000 foot soldiers out onto the streets make any kind of sense.
Deutsche might say the payments are a contractual obligation, which only tells you the contracts are mad. For investors, the sensible way to measure this behaviour is to conclude that investment banks are run mostly in the interests of a very small number of investment bankers. Clients, certainly shareholders, come a distant second or third.Â
For at least the past five years, selling shares in Deutsche has been a good bet. There remains little reason to buy.