Their under-18s got the better of West of Scotland’s by 40-33 at the capital’s Hive Stadium and their under-16s beat Stirling County’s by 36-14 on next-door Murrayfield Stadium’s back pitches later on to add to the Gytes club’s celebrations.
The Borderers’ colts, captained by fly-half Liam Irvine, had to fight back from falling 26-12 behind by half-time to edge out their East Dunbartonshire opponents but came up with five unanswered tries on the trot to secure victory.
Their try-scorers were inside-centre Matthew Farndon and loosehead prop Cameron Grant at the double, tighthead prop William Hamilton and left-winger Ewan Miller, with Irvine converting five.
Touching down for their opposite numbers from Milngavie were Callum Cairns, Rory Caldwell twice, Finlay Semple and Sean Cronin, with Christian Ward adding four conversions.
Farndon was named as the Scottish Rugby Union’s man of the match.
“I’m really proud of the team,” skipper Irvine told the SRU’s Facebook page afterwards.
“We’d been training really hard towards this and we knew it was going to be tough.
“Thanks to West for giving us such a good game, but it was class to come out on top and lift the shield, so I’m happy with the boys.”
Making up the rest of the young Pees’ starting XV were Kieran Ross, Kyle Dickie, Andrew Haig, Sam Ferry, Lewis Carter, Ruaridh Dougherty, Alfie and Jasper King, Lewis Downie and George Brydon, with Alexander MacNeil, Aiden Hinks, Tom MacMillan, Gwion Roberts, Callum Ross and Findlay Boak as replacements.
Peebles’ under-16s, captained by hooker Paddy Thomson, led all the way, unlike their older counterparts, going into half-time 24-0 up and remaining in front by 22 points come the final whistle.
Openside flanker Sam Brown, tighthead prop Brian O’Hare, loosehead prop Oran Britton, scrum-half Ben Rainey at the double and openside flanker Sam Brown scored their tries, with inside-centre Andrew Black adding two conversions and outside-centre Toru Keen another.
Justin Davidson and Sean Torkington touched down for Stirling, with George Martin kicking both conversions.
Rainey was named as man of the match.
A club spokesperson welcomed that second victory of the day, saying: “The boys were absolutely fantastic, all 21 of them.
“The first five minutes are always a chance to set the tone, to state your intent, and the boys were so aggressive that Stirling just couldn’t get into the game.
“We’re so proud of the boys and happy that they managed to seize the moment and get the win in tough conditions.
“The club can be incredibly proud of this group of young men.”
Also in the Borderers’ starting line-up were Jack Campbell, Oliver Drummond, Geordie Calder, Ross Monro, Nathan Pirie, Robert Kerr, Ruaridh Pearson and Eddie Ferry, with Sam Hubert, Jackson McNab, Thomas Bartlett, Finlay Burns, Euan Tait and Stuart Whiteford on the substitutes’ bench.
Sunday’s other boys’ winners were Boroughmuir’s under-16s and Stirling’s under-18s, both collecting cups, with girls’ cups going to Cambuslang’s under-16s and Stirling’s under-18s and shields to Stirling’s under-16s and Dumfries Saints’ under-18s.
Sunday’s other boys’ finalists were Currie Chieftains’ under-16s and under-18s, beaten 20-15 by Boroughmuir and 36-24 by Stirling respectively.
This year’s other girls’ finalists were Biggar and Dundee’s under-16s and Biggar and Cambuslang’s under-18s.

1. Peebles U16s and U18s
Peebles’ under-18s celebrating beating West of Scotland 40-33 in Sunday’s national rugby youth shield final for their age in Edinburgh (Photo: Stephen Mathison) Photo: Stephen Mathison

2. Peebles Colts v West of Scotland under-18s
Peebles Colts players celebrating beating West of Scotland 40-33 in this year's under-18 national youth shield final at Edinburgh’s Hive Stadium on Sunday (Photo: Stephen Mathison) Photo: Stephen Mathison

3. Peebles under-16s v Stirling County under-16s
Ben Rainey with his award for player of the match after Peebles under-16s beat Stirling County under-16s in their age group’s national youth shield final at Edinburgh’s Murrayfield back pitches on Sunday (Photo: Stephen Mathison) Photo: Stephen Mathison

4. Peebles Colts v West of Scotland under-18s
Matthew Farndon, right, with his award for player of the match after Peebles Colts beat West of Scotland 40-33 in this year's under-18 national youth shield final at Edinburgh’s Hive Stadium on Sunday (Photo: Stephen Mathison) Photo: Stephen Mathison