In 2018, the UK updated the Misuse of Drugs Regulations 2001—not the 1971...

https://hectorzfzj813.image-perth.org/what-does-class-b-mean-for-cannabis-in-the-uk

In 2018, the UK updated the Misuse of Drugs Regulations 2001—not the 1971 Act—to allow specialist doctors to prescribe cannabis-based medicines like Sativex and Epidyolex. Despite this, cannabis remains a Class B drug for recreational use