Inspector Morse author Colin Dexter signed a book of memories when he returned to the offices of his former employer.

Mr Dexter worked for the Oxford and Cambridge exam board. Its former headquarters, Elsfield Hall, at Cutteslowe, is now the home of Oxford Psychologists Press, which produces personality tests used by employers to recruit and train staff.

The company's 80-strong workforce moved from cramped offices in Summertown into the red-brick 1930s building, which started life as a Territorial Army HQ.

Founder Robert McHenry said: "We used to see Colin walking by our window and started to speculate on the psychological make-up of Inspector Morse.

"He was the personification of a Jungian type known as Introverted, Intuitive, Thinking and Perceiving.

"With OPP's help, this kind of personality analysis is now widely used by many large companies to help them recruit and develop the right staff."

He added: "During the past 11 years, OPP has grown from three employees to 80 and, as Colin provided my small team with early inspiration, it is appropriate that he should open Elsfield Hall for us."