The following acts are considered now to be unlawful and cannot be shown in the UK
Spanking
Caning
Aggressive whipping
Penetration by any object “associated with violence”
Physical or verbal abuse (regardless of if consensual)
Urolagnia (known as “water sports”)
Role-playing as non-adults
Physical restraint
Humiliation
Female ejaculation
Strangulation
Facesitting
Fisting
http://legislation.data.gov.uk/cy/uksi/2014/2916/made/data.htm?wrap=true