Alan was in Gascony with King Edward I of England in October 1288, when he was one of the hostages given by the king to Alfonso of Aragon for the fulfillment of certain agreements. He was in Scotland in the King's service in June of 1291. In April 1294 he had a writ of protection from the King when he travelled overseas with the King's daughter, Eleanor of Bar. He served in Gascony in 1295 and 1296, and was present at the action around Bordeaux on March 28, 1296, when his standard bearer was captured by the French. In 1297 he was summoned for service in Flanders, and attended Councils in Rochester and London in that year.

He was summoned for service against the Scots in 1297-1313. He fought in the Vanguard at the Battle of Falkirk on July 22, 1298. King Edward's army at that battle consisted of 12,000 infantry, including 10,000 Welsh, and 2,000 cavalry. William Wallace, the Scottish leader accepted battle in a withdrawn defensive position. Wallace had few cavalry and few archers; but his solid "schiltrons" (circles) of spearmen were almost invincible. The armoured cavalry of the English vanguard were hurled back with severe losses. Edward brought up his Welsh archers in the intervals between the horsemen of the second line, concentrating their arrows on specific points in the Scottish schiltrons. It was into these gaps that the English knights forced their way, and once the Scottish order was broken the spearmen were quickly massacred. Alan was at the siege of Caerlaverock in July 1300.

He was summoned to Edward II's coronation on January 18, 1307/08. In December of that year he had a protection to go on a pilgrimage to Santiago de Compostela. He was the Constable of Rockingham Castle and the Keeper of the forests between the bridges of Oxford and Stamford.