On 15 June 1242 Alan was summoned to attend the king Henry III with horses and arms in Gascony. He was at La Sauve in October, at Bordeaux in March and April 1243, and at La Réole in November. Before 6 August 1250 Zouch was appointed justice of Chester and of the four cantreds in North Wales. Matthew Paris says that he got this office by outbidding his predecessor, John de Grey. He offered to pay a ferm of twelve hundred marks instead of five hundred. Zouch boasted that Wales was nearly all reduced to obedience to the English laws, but his high-handed acts provoked royal interference and censure. He continued in office as the Lord Edward's deputy after the king's grant of Chester and Wales to his eldest son.

During the barons' wars Zouch adhered to the king. He was on 9 July 1261 appointed sheriff of Northamptonshire, receiving in October a letter from the king urging him to keep his office despite any baronial interlopers. He remained sheriff until 1264, and sometimes ignored the provisions of Magna Carta by acting as justice itinerant in his own shire and also in Buckinghamshire and Hampshire. In 1261 he was also made justice of the forests south of Trent, and in 1263 king's seneschal. In April 1262 he held forest pleas at Worcester.

On 12 December 1263 he was one of the royalist barons who agreed to submit all points of dispute to the arbitration of Louis IX. According to some accounts he was taken prisoner early in the battle of Lewes by John Giffard. He escaped almost immediately and took refuge in Lewes Priory, where he is said to have been found after the fight disguised as a monk.

In the summer of 1266 he was one of the committee of twelve arbitrators appointed to arrange the terms of the surrender of Kenilworth Castle. On 23 June 1267, after the peace between Henry III and Gilbert de Clare, 8th Earl of Gloucester, he was appointed warden of London and constable of the Tower. He continued in office until Michaelmas, whereupon his tenure was prolonged until Easter 1268.

In 1270 Zouch had a suit against Earl Warenne with regard to a certain estate. On 19 June the trial was proceeding before the justices in banco at Westminster Hall, and Zouch seemed likely to win the case. He was murderously attacked by Earl Warenne and his followers. Roger, his son, was wounded and driven from the hall; Alan himself was seriously injured and left on the spot. He was still surviving when, on 4 August, Warenne made his peace with the crown and agreed to pay a substantial compensation to the injured Zouches. He died on 10 August, and on 20 October his son Roger received seisin of his estate.