Their marital break-up caused a sensation and their divorce, in 1670, on the grounds of Lady Roos's adultery, was the first to be granted in England since the Reformation.

[3] Lady Roos instead gave him the name "John", after the future duke, who introduced a parliamentary bill to have the child illegitimised.

Although an MP, Roos had taken little interest in Parliamentary proceedings until he began to seek support for his divorce.

She is believed to have married someone with the surname Vaughan, possibly the same man who was injured in a duel with Philip Herbert, 7th Earl of Pembroke, in the 1670s.

[8] Roos married Lady Diana Bruce in 1671, and went on to have legitimate children by his third wife, Catherine Wriothesley Noel.