He subsequently graduated in dentistry at University College London (1948–1953), and then trained in orthognathic surgery at Queen Victoria Hospital in East Grinstead (1953–1956).
Mew's orthodontic methods have consisted of widening and advancing the upper jaw using palatal expanders, changing the patient's diet, and having the patient adopt a myofunctionally correct resting place for the tongue, where he argues it provides an outward force able to laterally expand the upper jaw in a growing child, and prevent downward and backward growth of the maxilla, gradually resulting in a 'natural' cure of the malocclusion.
As part of his search for an approach to orthodontics that did not cause facial retraction, John Mew visited Rolf Fränkel in East Germany in 1968, who introduced him to the work of Konstantin Buteyko.
He practiced Orthotropics for 30 years and was involved in founding the International Association of Facial Growth Guidance in 1987 in Fort Worth, Texas.
[16] This coverage included many tabloid papers and an interview with John Mew’s son Michael on This Morning with Eamonn Holmes.
He appealed against the then Minister of Health in the High Court in 1987 and Lord Justice Murray Stuart-Smith judged that "these very serious strictures were wholly unwarranted and perhaps go some way to justify the applicant's doubts as to the impartiality of the Dental Services Committee".
[27] In 1963 he twice broke the Formula One club circuit record at Brands Hatch, beating times set by world champions Jim Clark, and John Surtees.
In 1971, he was selected to crew for John Prentice, captain for the British International 14 dinghy racing team in Annapolis, Maryland, where Britain came second.
[citation needed] Between 1993 and 1999, Mew built a reproduction moated castle in a valley in Sussex, which was featured on the TV programme Britain's Best Home.