Lord Snowdon, who was married to Princess Margaret, had gay affairs, the celebrity interior designer Nicky Haslam has claimed.

In a forthcoming memoir, Haslam, 69, alleges he had an affair in 1959 with Lord Snowdon, then known as Antony Armstrong-Jones, just a year before he married Princess Margaret.

He also said the peer had an affair with Tom Parr, later head of the luxury-goods firm Colefax and Fowler.

Haslam said he first met Lord Snowdon in 1955 at the age of 16 and began an affair with him four years later.

He wrote: “I had a very brief romance with Tony Armstrong-Jones, somewhat one-sided on my part as Tony, who was dazzlingly attractive, had other irons in the fire.”

However, Lord Snowdon, now 79, has poured cold water on the claims, saying: “It’s not true as far as I’m concerned – and I should know.”

The peer has been subject to rumours about his sexuality for decades but has never said he is bisexual.

When asked once in at a party in New York about the Queen’s health, Princess Margaret is said to have replied: “Which one? My sister, my mother or my husband?”