George Watson's College have emerged as the powerhouse of schools rugby in Scotland this season and the Edinburgh school will aim to achieve a double when they play in the Brewin Dolphin Cup finals at both under-18 and under-16 levels at Murrayfield tonight.

In the under-18 match, Watson's are firm favourites against Dundee High, who are making their first appearance in the final since 2005, when Richie Vernon, later to be a Glasgow Warriors back-row, was in the Mayfield side. Watson's have had an impressive season, losing only to Stewart's-Melville and the touring New Zealand side, Palmerston North Boys' High.

Ally Donaldson, Watson's director of rugby, reckons that the defeat by Palmerston North was a turning point in their season. "It proved to be a great learning experience for the boys," he said. "We were competitive with them for much of that match but they pulled away in the last quarter."

Watson's, who beat Merchiston in the final last year, showed their ability with a comfortable win over a strong Strathallan team in a high quality semi-final at Kirkcaldy earlier this month, following big wins over North Berwick High in the first round and Glasgow High in the quarters.

They will look to their captain and No.8 Ally Miller, who played for Scotland under-18 last season, for leadership, but they have quality too in hooker Jake Kerr and winger Ben Robbins, who won the famous New Year Sprint.

Dundee High return to the Murrayfield stage nine seasons after their last appearance when, for a second successive year, they lost to Dollar Academy. The Tayside school may be underdogs but, given the quality of some of their players, they could challenge Watson's.

They, too, are led from the back-row by flanker Chris Jollands, who, along with centre Duncan Leese, is in the Scotland under-18 squad. The Mayfield side also has national squad players in winger Ronan Joy and scrum-half Henry Samson, at under-17 level, and centre Ewan Fox, who is in the under-16 squad.

In the under-16 final, St Aloysius' College will bid to become the first Glasgow school to win a national title since Hutchesons' were under-15 champions. St Aloysius', under a new rugby director in Mark McKenzie, are strong at under-16 level, and confirmed it with a 11-5 semi-final win over Strathallan. Against a Watson's side, unbeaten this season, they face formidable opposition.