Cheltenham and Liverpool Lizards have retained the men's and women's British Water Polo Championships respectively.
In a repeat of last year's men's final, Cheltenham beat City of Manchester 11-10 thanks to Dave Taylor's late winner.
In the women's final, Liverpool Lizards beat City of Coventry 6-2 to win the national title for a second time.
Sunday's victories saw both Cheltenham and Liverpool complete a double of 2015 titles, after sealing their respective British League wins in January.
"It was a bit of a close affair," Cheltenham captain Taylor told BBC Sport. "Our club hadn't won the double since 1968, so we are over the moon."
Cheltenham coach James Ross added: "I'm very proud. We went so close to the double last year, narrowly missing out on the league, so it's nice to see the same group of lads progress this year."
Despite the result, City of Manchester captain Rob Rae was pleased with their performance.
"We came in to the Championships as underdogs," he told BBC Sport. "To lose with only one goal in it is a massive achievement for the lads.
"For them to score in the last 30 seconds to win the game just shows how competitive we were this year."
Meanwhile, hosts Lancaster beat Bristol Central 11-7 to claim the men's bronze, while City of Manchester won the women's third-place play-off for a second-year running, beating London Otter 9-8.
Liverpool Lizards captain and Olympian Fiona Pimblett said:
"Everyone at the club is over the moon with the win this weekend.
"Retaining the title is such a great achievement along with winning the British Waterpolo National League.
"The unbeaten streak we've had in the recent 18 months just shows the depth of talent that we have at the club with strong grassroot players coming through."