In 2018, UK cannabis law changed through an update to the Misuse of Drugs...
https://www.adirs-bookmarks.win/uk-cannabis-law-changed-in-2018-when-the-misuse-of-drugs-regulations-2001-were
In 2018, UK cannabis law changed through an update to the Misuse of Drugs Regulations 2001, not the Misuse of Drugs Act 1971