In 2018, UK cannabis law changed through the Misuse of Drugs Regulations 2001,...

https://wiki-burner.win/index.php/I_Thought_Cannabis_Was_Legal_in_the_UK_%E2%80%93_Why_Can_I_Still_Be_Arrested%3F

In 2018, UK cannabis law changed through the Misuse of Drugs Regulations 2001, not the 1971 Act