How married Princess Margaret's affair with 'toy boy' 18 years her junior threatened to damage the whole royal family

Yet again Queen Elizabeth's sister found her love life played out on the front pages of the country's newspapers when she started a relationship with Roddy Llewellyn while married to Lord Snowdon 

Her love life was as colourful as the stately robes of her sister, Queen Elizabeth II, and 40 years ago Princess Margaret's relationship with a man 18 years her junior made front page news.

What made the affair more scandalous was that the 43-year-old Princess was still married to Lord Snowdon.

It was the first time the private life had been played out in lurid detail in public, and set the tone for the coverage of the marriage troubles of both Charles and Diana and Andrew and Fergie decades later.

Margaret won a place in the hearts of the British public after she was deprived of her first love Peter Townsend in the 1950s, as fans of the Netflix drama The Crown will recall.