Those scores during the final eight minutes saw Ireland win their first Under-20 Grand Slam since 2007, a magnificent achievement given they were 10 points behind early on and played their final round clash without talismanic half-backs Harry Byrne and Craig Casey. It was the Ireland U-20s' maiden victory in four visits to Parc Eirias, a venue they travelled to already assured of a first U-20 Six Nations title in nine years.

Jonathan Wren's try just before half-time saw Noel McNamara's youngsters recover from a nervy start to trail 10-7, having gone behind to Aneurin Owens' 10th-minute try with Cai Evans, son of Welsh rugby great Ieuan Evans, kicking five points. The visitors had two tries from Scott Penny and Sean French disallowed as they were stopped just short of the line.

Healy and Cormac Foley both started at half-back, coming in as late changes for Byrne (hip flexor) and Casey (knee) who both fell just short in their injury recoveries. McNamara's unbeaten charges had to soak up the early pressure after a Tierney-Martin overthrow and a subsequent maul infringement, but the defence stood firm and Rhys Davies leaked a scrum penalty.

Nerves were certainly evident and the visitors duly fell behind, the defence being sucked in and Tomi Lewis took advantage of the space on the right wing to take on Jake Flannery on the outside and lob a pass back inside for centre Owen to finish off a well-worked try, which Evans converted. In response, Healy chased his own clever kick but was guilty of a high tackle on the covering Evans.

Ireland's first couple of attacks in the Welsh 22 had them inches away from a try. TMO Stuart Terheege ruled that Penny and French were short on both occasions, the Leinster flanker just inches away from driving in under the posts and strong-running centre French breaking a tackle off a scrum but the match officials adjudging that he knocked on as he stretched for the line.

Ireland captain Charlie Ryan was isolated on the ground, another error coughing up a penalty on the half hour mark which Evans brilliantly drilled over from just inside the Irish half. Wales continued to chop down Hodnett on the carry, slowing down the Irish attack, but finally some space opened up for the back-three late on and they ruthlessly took advantage.

Turnover ball was shipped out to Ulster's Angus Kernohan and he blazed up the right touchline, breaking past halfway and retaining possession. Wales scrambled back but quick ruck ball was moved to the left where Penny ran hard, absorbing a tackle and getting his hands free to find Wren who expertly cut in off his wing to evade the final defenders and touch down. Healy's conversion made it a three-point game.

Ireland upped the ante in a rain-hit third quarter, beginning with Penny's turnover-winning tackle on Wales captain Dewi Lake. Healy won the kicking battle to put his side back into scoring range and although the subsequent maul was grounded, the prolific Tierney-Martin bounced up and used his pace and power to crash over in the left corner. The TMO decision went Ireland's way this time, and Healy coolly added the extras for a 14-10 lead.

Evans converted for a 17-14 scoreline but he was wayward with a 63rd-minute penalty attempt from halfway, with a subsequent maul turnover allowing Ireland's replacement scrum half Reilly to quickly get his hands on the ball. Wales should have made more of a Tiaan Thomas-Wheeler break, but Kernohan came up trumps with a vital tackle on Conbeer and a subsequent penalty win.

Rob Russell, another of the Irish reserves, did well to defend a dangerous chip in his own 22 and his Dublin University club-mate Ryan Baird also made an impact in the lineout and as a ball carrier. The strength-in-depth was key on the night with John McKee punching a hole in midfield and then Reilly, spotting the absence of a pillar defender, showed terrific pace off the mark to spring clean through from a ruck, scoring past full-back Evans.

Flannery was unfortunate with the left-sided conversion which bounced away off the near post, leaving the game delicately poised at 19-17. Wales forced a turnover to give themselves a shot at replying, but Martin Moloney's breakdown skills won Ireland a relieving penalty. They worked their way downfield, sending a penalty to the left corner with just minutes remaining.

After the tiring Welsh pack denied the Irish maul, Buccaneers clubman Reilly used the ball intelligently from a penalty advantage with French's quick hands in midfield also proving important. The visitors' adventure was rewarded when Clarkson dived over from a close-range ruck. Flannery converted with the last kick, his team-mates erupting in celebration. The new U-20 Grand Slam champions were officially crowned when injured skipper David Hawkshaw joined Ryan to lift the trophy together.

Scorers: Wales Under-20s: Tries: Aneurin Owen, Jac Morgan; Cons: Cai Evans 2; Pen: Cai Evans

Ireland Under-20s: Tries: Jonathan Wren, Dylan Tierney-Martin, Colm Reilly, Thomas Clarkson; Cons: Ben Healy 2, Jake Flannery

HT: Wales Under-20s 10 Ireland Under-20s 7

TIME LINE: 10 minutes - Wales try: Aneurin Owen - 5-0; conversion: Cai Evans - 7-0; 29 mins - Wales penalty: Cai Evans - 10-0; 39 mins - Ireland try: Jonathan Wren - 10-5; conversion: Ben Healy - 10-7; Half-time - Wales 10 Ireland 7; 46 mins - Ireland try: Dylan Tierney-Martin - 10-12; conversion: Ben Healy - 10-14; 58 mins - Wales try: Jac Morgan - 15-14; conversion: Cai Evans - 17-14; 63 mins - Wales penalty: missed by Cai Evans - 17-14; 72 mins - Ireland try: Colm Reilly - 17-19; conversion: missed by Jake Flannery - 17-19; 79 mins - Ireland try: Thomas Clarkson - 17-24; conversion: Jake Flannery - 17-26; Full-time - Wales 17 Ireland 26

WALES U-20: Cai Evans (Ospreys); Tomi Lewis (Scarlets), Tiaan Thomas-Wheeler (Ospreys), Aneurin Owen (Dragons), Ioan Davies (Cardiff Blues); Sam Costelow (Leicester Tigers) Dafydd Buckland (Dragons); Rhys Davies (Ospreys), Dewi Lake (Ospreys) (capt), Ben Warren (Cardiff Blues), Ed Scragg (Dragons), Teddy Williams (Cardiff Blues), Ellis Thomas (Llanelli), Jac Morgan (Aberarvon/Scarlets), Iestyn Rees (Scarlets).

Replacements used: Will Griffiths (Dragons) for Lake, Tom Devine (Dragons) for R Davies, Jac Price (Scarlets) for Scragg, Ryan Conbeer (Scarlets) for I Davies (all 51 mins), Nick English (Bristol Bears) for Warren, Ioan Rhys Davies (Cardiff Blues) for Thomas (both 73). Not used: Dan Babos (Dragons), Max Llewellyn (Cardiff Blues).

IRELAND U-20: Jake Flannery (Shannon/Munster); Angus Kernohan (Queen's University/Ulster), Liam Turner (Dublin University/Leinster), Sean French (Cork Constitution/Munster), Jonathan Wren (Cork Constitution/Munster); Ben Healy (Garryowen/Munster), Cormac Foley (St. Mary's College/Leinster); Josh Wycherley (Young Munster/Munster), Dylan Tierney-Martin (Corinthians/Connacht), Thomas Clarkson (Dublin University/Leinster), Charlie Ryan (UCD/Leinster) (capt), Niall Murray (Buccaneers/Connacht), Martin Moloney (Old Belvedere/Leinster), Scott Penny (UCD/Leinster), John Hodnett (UCC/Munster).

Replacements used: Ryan Baird (Dublin University/Leinster) for Murray (48 mins), Rob Russell (Dublin University/Leinster) for Healy, Colm Reilly (Buccaneers/Connacht) for Foley, John McKee (Old Belvedere/Leinster) for Tierney-Martin (all 63), David McCann (Banbridge/Ulster) for Hodnett (71). Not used: Callum Reid (Banbridge/Ulster), Ryan Lomas (Galwegians/Connacht), Iwan Hughes (Ballynahinch/Ulster).

Referee: Christophe Ridley (England)