In the novel Death on the Nile, Lord Charles Windlesham is a friend of Linnet Ridgeway, Joanna Southwood and Toby Bryce. He went to Chez Ma Tante with them. The gossip column in the Daily Blague speculated that he was engaged to Linnet.
His family home is called Charltonbury, and his ancestors had held it since the time of Queen Elizabeth I.
At the beginning of the novel, Lord Windlesham is hopeful that Linnet will accept his proposal of marriage. She had previously refused, but that was not a definite refusal, and had been little more than a plea for time.
Lord Windlesham considered it advisable that he should marry money, but it was not such a necessity that he had to put his own feelings aside. He was genuinely in love with Linnet, and would have wanted to marry her even if she was penniless.
However, Linnet eventually turns Lord Windlesham down, and marries Simon Doyle instead. Lord Windlesham then goes to Canada.
Lord Windlesham does not appear in the 1978 Ustinov film adaptation. He does however make a brief appearance in the 2004 Suchet film adaptation. He is seen near the beginning just coming back from hunting with Tim Allerton. Joanna Southwood and Linnet Ridgeway see them from Linnet's bedroom window. Joanna tells Linnet that rumours have it that she and Windlesham are "halfway up the aisle". The actor does not have a speaking part and is not credited.