In the UK, a requirement for anchorage points was introduced in 1965, followed by the requirement in 1968 to fit three-point belts in the front outboard positions on all new cars and all existing cars back to 1965. Successive UK Governments proposed, but failed to deliver, seat belt legislation throughout the 1970s. Front seat belts were compulsory equipment on all new cars registered in the UK from 1972, although it did not become compulsory for them to be worn until 1983. Rear seat belts were compulsory equipment from 1986 and became compulsory for them to be worn in 1991. However, it has never been a legal requirement for cars registered before those dates to be fitted with seat belts. In one such attempt in 1979 similar claims for potential lives and injuries saved were advanced. William Rodgers, then Secretary of State for Transport in the Callaghan Labour Government (1976--1979), stated: ''On the best available evidence of accidents in this country - evidence which has not been seriously contested - compulsion could save up to 1000 lives and 10,000 injuries a year.''
Based on the above text, what's the best answer to this question: is it illegal to not wear a seatbelt in the backseat uk?
yes