Saturday's Vitality Blast final saw plenty of late action and drama, with Hampshire surviving the final delivery of the match due to a no-ball call.
Lancashire only managed a bye from the resulting free hit, giving Hampshire the win by a solitary run.
Hampshire's captain James Vince played a huge part, taking his team to the side to keep them motivated and focused, and as a result he lifted his third title following previous victories in 2010 and 2012.
Vince finished as this season's leading run-scorer, accruing 678 at an average of 48.42 and strike-rate of 146.12, but his leadership in a tight spot impressed overseas signing Nathan Ellis.
"Vincey was really good," Ellis said. "He let us take a breath and made sure everyone was aware of the situation. That went a long way for us to calm down, get our heads back and then have another go.
"He is definitely one of the calmer captains I've played under. On top of that, he has had an amazing tournament and led from the front with his actions and his performances. That is all you can ask for.
"It is actually a big role with the amount of cricket by playing in all formats. I can't imagine being up and about and being able to lead from the front day in, day out like he does. He's been phenomenal."
Vince, sitting next to the Australia seamer, chuckled: "Contract secured for next season."
Vince was a teenager when Hampshire beat Somerset in the 2010 final by virtue of losing fewer wickets and a similar scenario could have unfolded in Birmingham on Saturday. With the teams level on wickets lost, Lancashire required just two to tie and thus win because of a superior powerplay score.
Lancashire skipper Dane Vilas protested at the end that Gleeson and Tom Hartley had run a second bye from the last legitimate delivery but a dead ball had already been called by that point. Law 20.2 states "whether the ball is finally settled or not is a matter for the umpire alone to decide".
Vince believes the umpires may have erred from the final ball of the penultimate over in Hampshire's innings, claiming Lancashire only had three fielders inside the 30-yard ring rather than four.
"It felt like a few things went against us," Vince said. "When they had three inside the ring, they (the umpires) didn't look back at it and give us a no-ball, there's a couple of extra runs there.
"Finals, especially the ones we've played in, come down to one or two runs so it felt like they had the rub of the green a little bit so it's extra special to get over the line in the end."