With his arm placed gently around her waist, Philip May gives his then girlfriend Theresa Brasier a supportive hug.

It was June 1977 and Miss Brasier, then aged just 20 and glancing back at the camera with a knowing look, had just completed her final exams at Oxford University.

Almost 40 years on, the couple remain inseparable. Theresa May is on the verge of becoming the country’s next prime minister, an ambition which, friends told The Telegraph, she has harboured since the age of 18 when she first arrived at Oxford.

Mr May, “her rock”, could soon become Britain’s First Husband, the new Denis Thatcher. Three years after the photograph was taken, the couple married at the Church of St Mary the Virgin in Wheatley in Oxfordshire, where Miss Brasier’s father was vicar.