Lt Col Sir William James Allen KBE DSO[1] (15 October 1866 – 20 December 1947) was a Northern Irish unionist politician, soldier and businessman.

The House was a venue for the signing of the Ulster Covenant, a cause Allen promoted vigorously, against what he viewed as the imposition by the British Government of the Third Home Rule Bill.

Brownlow House also subsequently became his military HQ from 14 November 1914 onwards, where Allen helped raise and organise the basic training of the 16th (Pioneer) Battalion Royal Irish Rifles.

From 1913 to 1914 Allen was a key supporter of Lord Edward Carson of Duncairn and Sir James Craig in their campaign against the third Home Rule Bill.

On 22 June 1921, he was one of several officers invested as Knight Commander of the Order of the British Empire (KBE)[7] to mark the visit [8] of King George V and Queen Mary of Teck to officially open the new Parliament of Northern Ireland.