NINETEEN letters from Lord Louis Mountbatten to a former naval comrade turned inventor are up for auction at Sotheby’s in London next Tuesday.

The collection of quite revealing personal letters are from Mountbatten, whose family home was at Broadlands in Romsey, to Arthur Cotton.

Many concern Mountbatten’s involvement in his friend’s inventions and particularly the Repeating Gramophones Limited company.

Arthur Cotton was an old Etonian and Cambridge graduate, a friend and brother officer of Mountbatten in the Royal Navy.

Mountbatten, known by friends and family as Dickie, used his royal connections to promote Cotton’s products and in one letter writes: “The gramophone is a great success & HRH is delighted with it. He was so pleased with it that he always used to bring visitors up to it and ask them if it wasn’t the neatest thing they had ever seen.”

Mountbatten, who was killed by an IRA bomb in 1979, also tried to help his friend’s business by sending him a letter of introduction to composer Jerome Kern.

A later letter explains Mountbatten’s decision to resign as a company director and others concern his continued investment in Cotton’s troubled company.

Relationships became strained between the two – perhaps due to Cotton’s failing business – and there is a break in correspondence from 1925 to 1938.

Later correspondence is of a more formal nature and is often typed.

The collection is expected to sell for between £2,000 and £2,500.