Jack made his debut for Merrion as an 18 year old in 1915. There was little senior cricket played in Dublin that summer, or in any other wartime one, some of the major clubs had, in fact, virtually ceased to exist. However the Junior League continued and it was in this competition that he first appeared for the club which was to become so much part of his life. It was in fact as a bowler that he caught the attention, taking 8 wickets against Railway Union. 5 against CYM and 4 against Pembroke Wanderers 2nds. Despite his contributions, all three matches were lost heavily. Thereafter it became his batting that took the eye, though his first 50 for the Club, an undefeated 65 against Richmond Asylum, the eventual League winners in 1917, was also in a losing cause.

The summer of 1919 saw senor cricket return to Dublin but Merrion continued in junior ranks. However Jack was able to record his first century with a fine 102* against Old Belvedere, helping set up an 88 runs victory. He continued until the end of the 1923 season scoring consistently in junior cricket gaining an Interprovincial Cap against Ulster at this level in that year. Joined in the side by team-mates Frank Fryer and Cecil Little, he saw Leinster notch a win by 39 runs over Ulster.

Then his career was interrupted by the spirit of adventure. He was, at the time a junior civil servant. He decided to emigrate to the United States, in the words of the Merrion History, "To join his brothers and make his fortune." HIs departure was lamented not only at Anglesea Road, but also at Williamstown, where Blackrock missed their strong running centre. However after two years working in a shoe shop he returned to Dublin, just in time to play in the Intermediate League. Final against Leinster Seconds. The match was won by 58 runs, but Jack, back in his old position at No 1, failed to score. Perhaps he was out of practice and had not graced the famous Staten Island ground. Merrion posted a moderate 146, but the medium pace swing and cut of future Irish "one cap wonder" Rollie Shortt carried them to victory. Jack was not to return to the USA, instead he purchased a tobacconists which was to provide his main source of income until his retirement.

The following season saw the Club promoted to senior ranks, replacing UCD, who were no longer able to field a competitive side. Captaining the team, Jack showed the way with an undefeated 53 in the first match of the season, a friendly against YMCA. Towards the end of the summer he hit a crisp 79* v Railway Union, a match won convincingly by a margin of 146 runs.

He was, in all to score 10 fifties at competitive level, including successive scores of 66 and 86 against Phoenix and Pembroke respectively in 1929. Both matches were won with some ease. However Jack's main contribution to Merrion cricket during his playing days was probably as captain. Between 1926 and his last full season of 1942, he led the side for 10 seasons, including the triumphant year of 1940, when they carried off the Cup and League double. This feat, remarkable enough in all conscience was all the more so as the Club went through the season unbeaten, having won only a solitary League match in the preceding two years.

In his senior competitive career he scored 2868 runs at 16.27 and held 53 catches. His earlier bowling deeds were almost forgotten as he took only 3 wickets at just over 34 runs each.

Jack was, perhaps, rather fortunate to gain two Irish caps as there were certainly better opening batsmen available. HIs debut match came against The Catamarans at College Park in July 1929. The visitors were a team of young Indians, mostly students, resident in Britain at the time. They included the young Nawab of Pataudi, who would go on to play for both England and India, captaining the latter, a feat also, of course, achieved by his son. Pataudi was a fine batsman who scored a century in the Bodyline series, but is possibly best remembered for refusing to field on the leg side in that series. "His Highness has conscientious objections, " said Jardine and the Nawab had to wait until England had a new captain to resume his Test career. Also in the Catamarans side was all rounder Syed Nazir Ali, a powerful batsman and very useful fast medium bowler, who was to play two Tests for India, including their inaugural match at Lord's in 1932, and was a considerable force in London club cricket at the time.

Jack was one of four debutants in the match, he and two of the others, Frank Reddy and Dublin University opener Cormac Lloyd, being late replacements. The fourth was a certain JC Boucher. After the first day was washed out, the visitors sent Ireland in on a drying wicket. Nazir Ali proved a handful in these conditions and soon clean bowled Jack for 4. Bowled out cheaply, Ireland eventually recovered to win by 76 runs, thanks mainly to the bowling of Boucher and Tom Dixon, but Jack made little contribution to the victory. Nazir Ali had him again in the second innings, this time before he had scored. He was to make one father appearance, for a decidedly under strength side, against MCC in Cork the following season. In a two day match MCC began by posting 239. Jack and David Pigot - The First! - opened Ireland's reply but, though Pigot stood firm, Jack again failed. He was yorked by South African paceman Denjis Morkel for 2. Ireland collapsed and were forced to follow on. Rain came to their rescue after two early wickets had fallen, this time, however, Jack had not gone to the crease.

He played his last match at senior level in 1947 but that was far from the end of his Merrion connection. He was for many years the Club's Honorary Secretary a role he combined with as similar one for the Leinster Cricket Union for more than two decades. In their invaluable work "Merrion A History of The Cricket Club 1892 - 2010" Alan Little and Danny Parkinson provide a more appropriate summing up of John Alan O'Donnell than this writer could hope to provide, " A Merrion titan and a strong captain and character who suffered fools very heavily indeed, and who was the most wonderful servant to the Club down the years."

Edward Liddle, August 2011