The answer is the Wallabies in 1939. They arrived in Britain just as the 1939-45 war started and had to return home from whence they had come by boat. Thus it was that Ireland did not, in fact, play Australia for the first time until December 1947 and that proved to be a chastening experience for the Irish who lost by 16 points to three on the afternoon of December 6.
In 1927 a team representing New South Wales called the Waratahs came to Britain, Ireland and France. They played against Ireland, England, Scotland, Wales and France and beat Ireland, Wales and France. But those matches at the time were not granted international status. However, many years later that decision was changed and in 1986 the Australian Rugby Union officially granted the matches international status. Prior to that the IRFU had awarded caps to the Irish players retrospectively.
But that match in 1947 was the first time Ireland played the team officially called Australia. Ten years elapsed before the countries met again and the match took place at Lansdowne Road on January 18, 1958. So this year we celebrate the 50th anniversary of what turned out to be an historic occasion.
There had been some very close calls against the All Blacks and Springboks through the years and a few heavy defeats but Ireland had never beaten a major touring team. All that changed on that January afternoon half a century ago and in the most dramatic and exciting circumstances.
The Australians, under the leadership of Bob Davidson, had lost to Wales 9-3 a fortnight before they met Ireland. It was an Ireland side that included no fewer than six new caps and included in that sextet were some names later to leave an indelible mark on the Irish and international scene both as players and administrators of the highest quality.
Foremost among the six was hooker Ronnie Dawson. He was later to go on and captain Ireland and the Lions. He was the first man appointed coach to the Ireland team and coached the Lions in South Africa in 1968. Dawson represented Ireland for many years on the International Rugby Board and is a former president of the IRFU.
The other new caps were centre David Hewitt, later a distinguished Lion, second row Bill Mulcahy, who later captained Ireland and played for the Lions. His second row partner was Jim Stevenson, who gave outstanding service to the IRFU.
On the flanks were Jim Donaldson, who became chairman of the Ireland selection committee and Noel Murphy, who went on to captain Ireland, coach Ireland and the Lions and become president of the IRFU. He is currently one of Ireland's representatives on the International Board.
The only survivor from the team that played Australia ten years previously was the great and incomparable Jack Kyle (pictured), then nearing the end of his magnificent career.
His brother-in-law Noel Henderson was in the centre, a survivor from the Golden Era and he captained a team that included Paddy Berkery at full back, Tony O'Reilly on the right wing, Cecil Pedlow on the left wing, Andy Mulligan at scrum half, Paddy O'Donoghue (later to become secretary of the IRFU) and Gordon Wood were the props and Ronnie Kavanagh completed the back row with Murphy and Donaldson.
The match was played in wet and windy conditions and as it entered its closing stages it appeared it would be yet another near miss for Ireland against a touring side, as the Wallabies led 6-3. Then enter Henderson to take centre stage. He sent a high and long kick deep into Australian territory and Dawson marked his debut by following up, at pace, gathering the ball and scoring a try.
It was not converted, but the sides were level. Then came the dramatic climax that sent the crowd into ecstacy. With the crowd now in full voice, Hewitt intercepted and found Henderson at his side. Henderson had some way to go and with the spectators in full voice he made it to the line to win the match and fashion a famous victory.
Fifty years have gone by but the memories still linger on for those fortunate enough to have been present on an unforgettable occasion. Twelve of the men who played for Ireland that afternoon are, fortunately, still with us, the exceptions are Gordon Wood, Andy Mulligan and the hero of the hour, Noel Henderson.