The Glasgwegian, always his own harshest critic, admitted that his winning time did not flatter him but that it was all part of his build-up to what he intends to be a career high. This is, after all, a swimmer who is targeting not just gold in his native Glasgow but a world record.
Jamieson pipped Peaty by just 0.11 seconds to retain his title in 2min 11.89sec, with Stirling's Ross Murdoch taking bronze in 2:12.17.
Jamieson, who will be favourite to claim 200m gold on the opening night of the Games, said: "It was a pretty slow time but I've just been trying to go through the motions and think of it as a training session. My main job now is to rest up and make sure I'm fully ready for the Commonwealth Games."
Roberto Pavoni retained his 400m individual medley title in a time of 4:21.80, while Bath's Jemma Barton took gold in the women's 200m butterfly ahead of Georgia Barton.
Other winners included Chris Walker-Hebborn, who retained his 100m backstroke title, Amy Smith, who took the women's 50m freestyle in 25.30 seconds, and Ben Proud, who took his second gold of the meet in the 50m butterfly.