The couple’s union was rumoured to be ill-fated from the start, as highlighted in Anne de Courcy’s recent biography of Snowdon on which this intriguing insight into their lives is based.

Tales of his waspish cruelty, boorish behaviour, extramarital affairs and illegitimate children are mere surface details in this one-hour exposé that is  likely to ruffle royal feathers.

When the couple divorced in 1978, blame for the marriage breakdown was heaped on Margaret, but it was a very different story, according to this programme.