Daughter of the Earl of Suffolk, little is known of Kate’s early years or education. In May 1638 she secretly married Lord George Stuart, ninth Seigneur d’Aubigny and second son of the Duke of Lennox. Clearly, it was a love-match; less clear is why neither Kate’s parents nor the King, who was guardian to the Stuart brothers, would consent to the match. But the young pair did it anyway and had it commemorated in two sumptuous portraits by Van Dyck. The one of George (now in the National Portrait Gallery) bears the motto, ‘Love is stronger than I am’.
The couple had two children. Tragically, however, George was killed at the battle of Edgehill in October 1642 leaving his young widow not just heart-broken but in financial difficulties. Since George hadn’t made a will, Kate couldn’t gain access to his money.
In May 1643, she got Parliament’s permission to come to London to deal with her husband’s affairs. Kate used this opportunity to deliver the King’s Commission of Array (aimed at raising forces among royalist sympathizers in the city) to fellow-conspirator Edmund Waller. It’s said she frequently carried secret messages hidden in her curls! Unfortunately, the Waller Plot was betrayed and some of the obscurer figures involved in it were hanged by Parliament. Kate claimed the protection of the French ambassador, by virtue of her husband’s French title, but was none the less imprisoned in the Tower for some months.
By late 1648 Katherine had married her second husband, a Scottish gentleman of the bedchamber to the King – James Livingston, Viscount Newburgh. They did not have children.
In December 1648, only weeks before his trial and execution, Charles I spent a night at the Newburghs’ house in Surrey, on his way from the Isle of Wight to Windsor, and the couple seem to have made some attempt to secure his escape. Their plans were foiled by the precautions of Major-General Thomas Harrison, but they were able to pass messages from Charles to his exiled queen.
Following the regicide the Newburghs joined other royalist exiles at The Hague. Kate died there in 1650 and was survived by her husband, who was created Earl of Newburgh in 1660 on the Restoration.