Highway Code Rule 99
You MUST wear a seat belt in cars, vans and other goods vehicles if one is fitted (see table below). Adults, and children aged 14 years and over, MUST use a seat belt or child restraint, where fitted, when seated in minibuses, buses and coaches. Exemptions are allowed for the holders of medical exemption certificates and those making deliveries or collections in goods vehicles when travelling less than 50 metres (approx 162 feet). ...
(taken from highwaycode.org btw and THEIR caps, not MINE.)
... Seat belt requirements. This table summarises the main legal requirements for wearing seat belts in cars, vans and other goods vehicles. ...
Laws
Seat belt requirements. This table summarises the main legal requirements for wearing seat belts in cars, vans and other goods vehicles.
Front seat
Rear seat
Who is responsible?
Driver
Seat belt MUST be worn if fitted
–
Driver
Child under 3 years of age
Correct child restraint MUST be used
Correct child restraint MUST be used. If one is not available in a taxi, may travel unrestrained.
Driver
Child from 3rd birthday up to 1.35 metres in height (or 12th birthday, whichever they reach first)
Correct child restraint MUST be used
Correct child restraint MUST be used where seat belts fitted. MUST use adult belt if correct child restraint is not available in a licensed taxi or private hire vehicle, or for reasons of unexpected necessity over a short distance, or if two occupied restraints prevent fitment of a third.
Driver
Child over 1.35 metres (approx 4ft 5ins) in height or 12 or 13 years
Seat belt MUST be worn if available
Seat belt MUST be worn if available
Driver
Adult passengers aged 14 and over
Seat belt MUST be worn if available
Seat belt MUST be worn if available
Sorry. I've had a really arsey day/week/month/year/decade/life. I did not mean to come across as arsey, but I did. My bad.
The above guidance, taken online from highway code, does indicate that the Driver Is Responsible for ensuring that any child From Age 14 wears a seatbelt.
Maybe I've been super clued up on this cos my kid was so tall she was out of a kid car seat and in a seatbelt from the age of about 12, if not earler (it's all a bit of a blur...)