The Road Vehicles (Construction and Use) (Amendment) Regulations 2018

Regulation 110 of the Road Vehicles (Construction and Use) Regulations 1986 (“the 1986 Regulations”) prohibits the use, while driving a motor vehicle, of hand-held mobile telephones or other hand-held devices, when performing an interactive communication function.

Link: The Road Vehicles (Construction and Use) (Amendment) Regulations 2018
Source: Legislation .gov.uk