Lucius and Catherine were married in the early months of 1701, "according to the rights and ceremonies of the Church of Ireland", and the Agreement was signed by Donat his friend Sir Thomas Southwell, Simon Purdon and Henry, Lord Shelbourne.

The couple started their married life at Stonehall, a property belonging to Donat, and which a short time later became the residence of Henry and Susannah Stafford O'Brien.

Lucius accumulated heavy debts of over £3,000 and despite numerous visits to the court, and even a private interview with the Queen, he was not able to secure the governorship of the Bahamas which he craved.

When the new king, George I arrived in England from Hanover, he brought his own retinue of attendants and favourites, which did not include Queen Sophia, who was in prison on a charge of adultery.

In 1715 Lucius broke his arm and visited a bone setter, he made sure his own doctor from Ireland, Denis Hickie (the Hickey's were hereditary physicians of the O'Briens), was present.

Feeling again that he might he discovered in so public a place, he and Dr. Hickie went to Versailles, "where he was taken with a mighty Melancholy which made him desire the Dr. to leave him alone, & come to Paris, which he did for 3 weeks".

In the end, as his friend, Jim Macnamara, described, he was "bury’d after a most despicable manner about 12 a’clock the ensueing night, being carry’d in a Dung Cart into a garden wherein the Swedish envoy has priveledge to have his people interr’d."