In the sides' previous meetings this season, there had been two draws and a single-goal win for the Londoners. This time, after another nail-biting finish, it was Manchester who prevailed - 12-11.
Manchester seemed to have the game under control in a dominant second period, when they went from 3-3 to 8-3, with goals by Dan Paddon, Kai Dowling and Rory Inman, plus a couple of sharp man-up finishes by Jordan Elliot.
It was 9-6 to Manchester after three periods but Penguin battled on, recovering to trail 10-8 and then, thanks to a couple of goals from Harry Dunkerley, 12-10. Just 47 seconds remained when Andrea Tulli converted a penalty for Penguin, who then won possession and called a time-out with 20 seconds remaining.
Manchester pressed hard . . . and held out - no doubt grateful to goalkeeper Tom Manley for some brilliant saves at key points in the game.
Earlier, Polytechnic eased into the final with a 17-7 victory over Sutton & Cheam. The Championship 1 winners made a spirited start. They were 2-1 ahead after the first period - their goalkeeper Matt Holland saved a penalty - and trailed only 5-4 midway through the second.
Then Poly, bidding to complete a League and Champions League double, took charge. It was 7-5 after two quarters, rapidly improved to 12-6 in the third, including three smart goals by Liam Neill, the top marksman in BWPL Super 5s this season.