Blackrock College emerged victorious from a Bank of Ireland Leinster Rugby Schools Junior Cup final of swinging fortunes at Donnybrook, newly christened as Energia Park, on Wednesday.

The Williamstown school set the tone from the kick-off, their lock Rory McGuire bounding forward through arm tackles for 30 metres.

Left wing Michael Nealon twice threatened down the touchline where he was met by St Mary’s College scrum-half Seanán Devereux the first time and centre Rob Nolan the second.

The adrenalin was up and McGuire was yellow carded for a high tackle to allow St Mary’s an access point at the lineout.

That man Nolan came on a hard line where Ben Brownlee was waiting to dislodge the ball.

Leinster Rugby Schools Junior Cup

It was Nolan with the tackle on number eight Sean Dempsey and into hooker Milo Byrnes, the latter leaving the field on the advice of touch judge Susan Carty.

St Mary’s looked like Ireland in disguise as they probed from an attacking lineout, centre Barra O’Loughlin making the biggest dent ahead of captain Adam Mulvihill’s dive to the line for full-back Max Svejdar to convert for 7-0 in the 11th minute.

This was just the tonic they needed to fuel their confidence, moving the ball sweetly until McGuire and prop Scott Barron countered at the ruck.

Leinster Rugby Schools Junior Cup

The counter ruck came in handy again on foot of Brownlee’s thunderous tackle on O’Loughlin.

This was all the invitation ‘Rock needed, wing Harry Whelan testing out Svejdar’s tackle technique, the ball brought back to the left for centre Tom Henderson to squeeze in at the posts, out-half Michael Moloney converting in the 19th minute.

This did not turn the tide as St Mary’s returned to attack, preferring the hard driving of their forwards to the men further out.

Leinster Rugby Schools Junior Cup

Their patience was a virtue until McGuire got in amongst them to cause a turnover.

St Mary’s switched it up by spreading the play wide where ‘Rock lock Naoise Golden eventually got in on the ball for a penalty turnover.

Blackrock had a clear advantage in speed on the outside and Nealon had to be shunted into touch by Ross Moore.

Leinster Rugby Schools Junior Cup

The weight of pressure was starting to tell, St Mary’s brave defence keeping McGuire and prop Scott Barron held up off the floor before Brownlee just about got downward pressure for Moloney to make it 14-7 at the break.

Blackrock were a different proposition when they came back out, mixing power and pace to draw a penalty for Moloney to make it 17-7 in the 33rd minute.

Left wing Nealon went close to their third from a kick ahead, Svejdar covering quickly to win the footrace.

The character of St Mary’s came to the fore. They refused to break, playing their best rugby of the competition in adversity to drive the ball and move it cleanly.

Leinster Rugby Schools Junior Cup

All the while, Blackrock soaked up the carriers until St Mary’s lock Daniel Leane spun out of a tackle for a hard-earned try, converted by Svejdar in the 45th minute.

The Rathmines school continued to play a lot of ball in their own half in an understandable tactic.

They just couldn’t find the right exit door and replacement hooker Max Patterson was the tail gunner of a ‘Rock maul that made it all the way for Moloney to convert in the 56th minute and secure the Cup.

At Donnybrook – Blackrock College 24 (T Henderson, B Brownlee, M Patterson try each; M Moloney pen, 3 cons); St Mary’s College 14 (A Mulvihill, D Leane try; A Svejdar 2 cons).

Blackrock College: Cormac O’Brien; Michael Nealon, Tom Henderson, Ben Brownlee, Michael Nealon; Michael Moloney, Thomas Quinn; David Walsh, Milo Byrnes, Scott Barron, Naoise Golden, Rory McGuire, Alex Simpson, James Culhane (capt), Sean Dempsey.

Replacements: Max Patterson for Byrnes 7 mins; Sam Loscher for Walsh 38 mins; Cian Moloney for Simpson 51 mins; Dylan Stafford for M Moloney 56 mins.

St Mary’s College: Max Svedjar; Ross Moore, Rob Nolan, Barra O’Loughlin, Sam Czerniek; Daragh Gilbourne, Senan Devereux; Collum Dillon, Matthew Black, Adam Mulvihill (capt), Daniel Leane, Hugo Massey, Will Sparrow, John Kennedy, Adam Sloan.

Replacements: Andrew Gibbons for Dillon, Matthew Gallagher for Massey, Garrett O’Moore for Sparrow all 33 mins; Euan Feeney for Gilbounre 36 mins.

Referee: C Hogan, Leinster Branch.