But the Welsh replied with a lineout drive of their own to make the score 5-5.
Left winger Sam Bushell then made the score 10-5 to the Irish before a real period of Welsh dominance left the Irish trailing at half-time.
A penalty straight in front and a crash ball run from their centre left the half-time score at 15-10 in the Welsh's favour.
The second half proved to be one-way traffic as the Irish opened with a converted try from inside centre Peter Brocken, added a second converted try by Sam Bushell.
And then a third try occurred when replacement full-back Matthew Dever was tackled but he fed the ball off for replacement right winger Christian Paget to score.
Out-half Grant Connon again converted to make the final score 31-15.
In other Exiles news, this coming Sunday, the Exiles Under-20s face their second challenge of the season when they play Cambridge University Under-21s at St. Mary's University College, Twickenham (kick-off 2pm).
After a narrow defeat to Ulster, the Exiles are determined to put matters right.
Representative calls affect the line-up, as three Exiles have been selected for the first Ireland Under-20 squad commencing the same day (Oliver Day, Ciaran Ruddock and Elliott O'Brien).
Injuries will also remove another two from the scene, but the Exiles remain confident with Ireland Under-18 half-backs of two seasons ago - Charlie Mulchrone and Matt Keville - reunited again.