Clongowes led 9-3 mid-way through the second half but once Rock got their noses in front there was only ever going to be one winner.
In the opening half Clongowes enjoyed the advantage in both possession and territory. Outside of full-back Robert Kearney, the liveliest of the Clongowes backs was centre, Dan O'Connor whose opening break after ten minutes took play from outside the Clongowes 22 to the Blackrock equivalent and send out a clear warning that there was more to the Clongowes attack than just their number 15.
The first real chance came the way of Clongowes after 11 minutes when number 14 Richard McElwee pinned his ears back and made good headway down the right. He really should have passed inside where the support was to provide the opening score. However Rock were penalised and Kearney tapped over the penalty to give the underdogs the lead.
They increased that to six in the 16th minute when Kearney lashed over another penalty after a period of Clongowes pressure.
Six points behind at the break, and never mind any allowance for injury, Blackrock had the use of the wind in the second half.
They reduced the deficit after just 3 minutes when out-half David Barnett judged the wind perfectly to land a penalty from the right of the posts (6-3).
Clongowes continued to defend tenacously and when Barnett attempted chip was blocked down it set up the field position for Pierce Casey to land a drop-goal into the wind (9-3).
There followed a period of intense Blackrock forward pressure which eventually yielded a try from captain Diarmuid Laffan after a series of drives at the Clongowes line and Barnett converted to put the favourites in the lead with 11 minutes of normal time remaining.
They put the outcome beyond doubt with less than three minutes to go when Michael Kavanagh finished off a good move foe his side's second try, Barnett again obliging with the conversion as Blackrock headed for their 64th title.
The final scoreline was given a flattering hue when Conor O'Daly scampered over for his side's third try.
Blackrock College: D Nyhan; M Kavanagh, L Fitzgerald, J Power, V Artemiev; D Barnett, D Madigan; G Walsh, C Culliton, S Snell, M Cantrell, R O'Hara, D Laffan, G Flanagan, D O'Reilly capt.
Clongowes Wood College: R Kearney; R McElwee, F McFadden, D O'Connor, K Stafford; P Casey, L Ronan; D Halpin, M Jacobs, P Crilly, T Sheils, D Fagan, B Coyle, P Lennon, P O'Meara capt. Replacements: James Rooney, Simon Kelly, Hugh Hackett.
Referee: Alan Lewis.
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