Janvrin entered the Royal Navy in 1964, was commissioned as an acting sub-lieutenant on 1 September 1966,[2] promoted lieutenant on 4 March 1971,[3] and served until 2 July 1975.

[5] Janvrin was First Secretary in New Delhi from 1981 to 1984, during which time he was made a member of the 4th Class of the Royal Victorian Order[6] for services during the Queen's state visit to India.

[15] He was promoted to Knight Grand Cross of the Order of the Bath in the 2007 Birthday Honours[16] and, on 24 July, it was announced that Janvrin would be made a life peer, as one of the ten public servants per Parliament whom the Prime Minister may nominate for a peerage upon their retirement.

[17][18] His title was gazetted as Baron Janvrin, of Chalford Hill in the County of Gloucestershire on 10 October,[19] and he sits as a crossbencher in the House of Lords.

Janvrin was portrayed by Roger Allam in Stephen Frears' The Queen (2006) starring Oscar-winner Dame Helen Mirren.

In episode 4, "Aftermath", Janvrin is depicted informing the Queen, Prince Charles, and The Duke of Edinburgh of the death of Diana, Princess of Wales.