Nanny has a thing about drugs, she is worried that even the mere association with a banned substance will lead to the moral and mental decline of her "charges".
Additionally, as she is a middle class Islingtonite, she really doesn't care much for those smelly fox hunting types who inhabit the countryside; in particular, she hates farmers.
Therefore she has decided to give them a good "seeing to", and eliminate the curse of drugs from this sceptered isle once and for all.
She has decreed that farmers with magic mushrooms growing on their property could be arrested for possession of controlled drugs.
Seemingly there are 12 varieties of magic mushroom that grow wild in the autumn; these have a powerful hallucinogenic effect similar to LSD. The main type is called liberty cap (Psilocybe semilanceata).
Believe it or not these mushrooms are quite common in the fields of Britain, and indeed elsewhere.
Now, the Drugs Act 2005 made the mushrooms a controlled drug; it is an offence to possess controlled drugs under the Misuse of Drugs Act 1971.
Before this typically rushed and ill thought out piece of legislation was nodded through by Nanny's lackeys, it was only an offence to possess the hallucinogenic ingredients of the mushrooms, psilocin and psilocybin.
The effect of this legislation will be to open the door for Nanny to prosecute farmers, for unwittingly growing the wrong sort of mushrooms in their fields.
Doesn't Nanny have anything better to with her time?