Champions Clongowes fell behind to Robert Troy’s expertly-struck fourth-minute penalty but the front row combination of the outstanding Byrne twins, Brian and Edward, and Daniel O’Byrne quickly put Castleknock on the back foot.
Hooker Brian Byrne was the catalyst for their opening score, shrugging off two tackles to ground the ball in the 26th minute before full-back Max McFarland finished off a lightning counter in the 29th. Conor Mahony converted both tries.
Jack O’Neill, Paul Nalty and Ahmad Mu’Azzam tried to keep Castleknock in the game but their hard work was undone as Brian Byrne forced a penalty for Mahony to make it 17-3 at the interval.
The Byrne twins were then heavily involved in paving a path for openside Stephen Keelan’s try, converted by Mahony, before wing Niall Rhatigan speared through for the fifth try in the 65th minute.
However, the losers did provide the best try of the day when full-back Eoghain Quinn sprinted half the length of the field to touch down in the final minutes.
Scorers for Clongowes Wood College: Tries: M McFarland 2, S Keelan, B Byrne, N Rhatigan. Pen: C Mahony. Cons: C Mahony 3
Scorers for Castleknock College: Try: E Quinn. Pen: R Troy.
CLONGOWES WOOD: M McFarland; C Mahony, C O’Hanrahan, S Fromm, N Rhatigan; M Nicholson, C McQuaid; E Byrne (capt), B Byrne, D O’Byrne, J Paul, R Daly, J Wallace, S Keelan, P Timmins.
Replacements: G McVerry for Fromm (31); S Mulholland for Timmins (40); J Sullivan for Nicholson (63); D Garty for E Byrne (68); K Cowhey for Keelan, C O’Donoghue for Rhatigan, D Donnellan for B Byrne (all 69).
CASTLEKNOCK: E Quinn; M Mellett, T Farrell (capt), D Sweeney, S McEntaggart; R Troy, D Henry; M Bennett, D Perry, O McEvitt, E Murphy, A Mu’Azzam, S Carroll, J O’Neill, P Nalty.
Replacements: J McCormack for McEntaggart (ht); E Hanlon for Troy (58); K Scanlon for Perry, S Condon for Carroll (both 60); J Burke for Henry (66).
Referee: P Haycock (Lein).