One save in a penalty shoot-out finally ended Deeping Rangers’ unbeaten run.
They produced second-half equalisers from prolific pair Nathan Pickering and Alfie Ferguson to force extra-time.
But Ferguson’s spot-kick was kept out by player of the match George Hunter to make the difference as Birchwood Colts converted five penalties.
Deeping have collected the PFA Under-15 Cup as well as the Peterborough & District Youth League’s Knockout Cup while they will be hoping to add the Division One championship.
However, they just missed out in Saturday’s Lincolnshire FA Under-16 Cup final.
Deeping created plenty of chances but trailed to Jake Soper’s header and a clinical finish by Rhys Patten.
Ferguson set up Pickering to lob Hunter and defender Joe Marshall just seven minutes into the second half.
Ferguson levelled again for Deeping with a 25-yard drive into the top corner with only 10 minutes left.
Nathan Lane almost won it with the last touch in stoppage-time after 80 minutes and then Rangers had more opportunities in 20 minutes of extra-time.
Manager John Carver said: “When it goes to penalties, you never know what’s going to happen.
We are obviously not used to losing and it can be quite difficult to take. We intend to come back in next year’s final.John Carver
“Overall we gave a good account of ourselves and their goalkeeper getting the man-of-the-match award was a good reflection of the game.
“We looked strong and we matched them in all areas of the pitch. We had chances to win it.
“We’ve won two cups and we are challenging for the title but we hadn’t lost for more than three years.
“This was our 86th game since a defeat so we had a few words in the changing-room after the match to reflect on the size of our achievements.
“We are obviously not used to losing and it can be quite difficult to take. We intend to come back in next year’s final.”
Meanwhile, Deeping face Baston in the under-12 final at Stamford on Friday (7pm).
The majority of the players are friends on the same side for the school team.
DEEPING RANGERS U15
4-1-3-2: Conway; Burutsa, Baldock-Smith, Barrand, Carver; Haggett-King; Moroz, Scales, Dee; Lane, Pickering. Subs: Ferguson, Piddington, Baxter, Banham.
4-5-1: Hunter; Cook, Soper, J Hobson, Quinn; D Hobson, Mumby, Coles, Durkin, Fenton; Patten. Subs: Birkinshaw, Marshall, Stubbs, Sanders.
Soper (23 mins, 0-1); Pickering (47 mins, 1-1); Patten (58 mins, 1-2); Ferguson (70 mins, 2-2).
Stubbs (0-1 Birchwood); Moroz (1-1); Quinn (1-2); Ferguson (saved by Hunter); Mumby (1-3); Pickering (2-3); Coles (2-4); Barrand (3-4); Fenton (3-5).
Marshall (handball); Haggett-King (foul).