England U20 completed a first Grand Slam in six years after defeating Ireland 14-10 at Donnybrook on Friday.
In the end the Six Nations champions outscored Ireland by two tries to one, thanks to scores from Jack Nay and Henry Walker in the first half.
A second-half try from Ireland U20 replacement Gavin Coombes brought the game to life to set up a tense closing stage for England with the Grand Slam on the line.
And despite some nervous moments the side coached by Ian Vass clung on, sparking wild celebrations in the Irish capital.
Second-row Nay opened the scoring for the visitors after 18 minutes, with Ireland fly-half Bill Johnston responding from a penalty to make the score 7-3.
England debutant Walker then gave his side a healthy lead when he stepped around Johnston to score right before half-time, with Max Malins adding his second conversion.
Coombes then went over in the 64th minute after persistent pressure and despite Ireland hammering away at the English defence in the final minutes, Ireland were held up over the line, giving England a dramatic victory.
Tries: Nay, Walker
Cons: Malins 2
Ireland: 15 Jordan Larmour, 14 Tommy O’Brien, 13 Gavin Mullin 12 Ciaran Frawley, 11 Calvin Nash (c), 10 Bill Johnston, 9 Jonny Stewart, 8 Caelan Doris, 7 Paul Boyle, 6 John Foley, 5 Oisin Dowling, 4 Fineen Wycherley, 3 Charlie Connolly, 2 Tadgh McElroy, 1 Joey Conway
Replacements: 16 Ronan Kelleher, 17 Greg McGrath, 18 Matthew Burke, 19 Jack Regan, 20 Gavin Coombes, 21 Jack Stafford, 22 Conor Fitzgerald, 23 Colm Hogan
England: 15 Tom Parton, 14 Joe Cokanasiga, 13 Dominic Morris, 12 Will Butler, 11 Sam Aspland-Robinson, 10 Max Malins, 9 Harry Randall, 8 Zach Mercer (c), 7 Ben Curry, 6 Tom Curry, 5 Nick Isiekwe, 4 Jack Nay, 3 Ciaran Knight, 2 Henry Walker, 1 Ollie Dawe
Replacements: 16 Jamie Blamire, 17 Ralph Adams-Hale, 18 Joseph Morris, 19 Justin Clegg, 20 Josh Bayliss, 21 Alex Mitchell, 22 Theo Brophy Clews, 23 Max Wright
Referee: Pierre Brousset (France)
Assistant Referees: Tual Trainini (France), Stéphane Boyer (France)
TMO: Arnaud Blondel (France)