Lord Ulster married her on 22 June 2002 at the Queen's Chapel, St James's Palace, following which her title became Countess of Ulster or Lady Ulster (as appropriate).
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Claire Alexandra Windsor, Countess of Ulster (née Booth; born 29 December 1977) is the wife of Alexander Windsor, Earl of Ulster, the son and heir of Prince Richard, Duke of Gloucester, and Birgitte, Duchess of Gloucester.
James Earl Jones | Prince Edward, Earl of Wessex | Louis Mountbatten, 1st Earl Mountbatten of Burma | Herbert Kitchener, 1st Earl Kitchener | Ulster | Earl | Frederick Roberts, 1st Earl Roberts | Earl of Derby | Earl Warren | Earl of Pembroke | Robert Harley, 1st Earl of Oxford and Earl Mortimer | Earl of Warwick | Ulster Unionist Party | Thomas Wentworth, 1st Earl of Strafford | Edward Smith-Stanley, 14th Earl of Derby | Earl of Shrewsbury | William Pitt, 1st Earl of Chatham | Simon de Montfort, 6th Earl of Leicester | Richard Neville, 16th Earl of Warwick | Earl of Leicester | John Scott, 1st Earl of Eldon | University of Ulster | Robert Devereux, 2nd Earl of Essex | Robert, 1st Earl of Gloucester | Edward Harley, 2nd Earl of Oxford and Earl Mortimer | Earl of Devon | Douglas Haig, 1st Earl Haig | Ulster loyalism | My Name Is Earl | Edward Hyde, 1st Earl of Clarendon |
The borders were expanded as land lost in the 13th century to the Earl of Ulster was regained at the expense of the Burke of Clanricarde.
After Walter de Burgh became Earl of Ulster in 1243 the de Burgh cross was combined with the Red Hand to create the modern Flag of Ulster.
Edmund de Mortimer, 3rd Earl of March and jure uxoris Earl of Ulster (1 February 1352 – 27 December 1381) was son of Roger Mortimer, 2nd Earl of March, by his wife Philippa, daughter of William Montagu, 1st Earl of Salisbury and Catherine Grandison.