The step up in class proved too much for Mount Temple with a determined St Mary's pack swamping them at the Mount Temple sports ground yesterday.
Lineout jumpers Niall Conway and Ciaran Lennon provided the launch pad for several attacks. Despite admirably defending, Mount Temple trailed at half-time 25-0.
Right wing James Clarke twice went over in the corner. A conversion and penalty from Gavin Cullen extended the St Mary's lead with Ronan O' Doherty adding to his team's tally. And then just before the break, Clarke completed his hat-trick.
For the second half, St Mary's introduced Leinster schools' back row Ciaran Potts, returning after a knee injury. He was among St Mary's three try scorers after the break along with Micheal Ryan and James Ryan.
ST MARY'S COLLEGE: I O'Herlihy; J Clarke, S Grissing, G Cullen, R O'Doherty; M Ryan, G O'Brien (capt); D Ryan, B McCormack, C O'Byrne, N Conway, R McArdle, C Lennon, J Ryan, D O'Brien. Replacements: E Kelly for Ryan (32 mins), F O'Sullivan for McArdle, C Potts for Conway (both half-time).
MOUNT TEMPLE: S Finnegan; J Gavin, D Moore, C Scott-Keogh, D Quirke; I Kelly (capt), R Maybury; J Kennedy, M Finglas, N Leonard, T O'Mahony, D Milne, G Kells, J Fitzachary, D Ffrench. Replacements: S Miller for Quirke (halftime), D Hashish for Gavin (61 mins), R RossMurray for Leonard, P Fearns for Finnegan, Quirke for Kells (all 65 mins).
Referee: G McFadden (ARLB).