England, too, had a third place to celebrate thanks to Tancock.
The Exeter swimmer was only the fifth fastest qualifier for the 50m backstroke final but the Delhi 2010 gold medallist touched in third behind Australians Ben Treffers, 22, and Mitch Larkin, 21.
England’s Chris Walker-Hebborn, 24, failed in his bid to add the 50m title to his 100m crown, finishing fourth. Wales’ Marco Loughran, 25, was sixth.
That race continued the ongoing dominance of Australia in the pool, after they won five of the first six medals available in Sunday’s programme.
Belinda Hocking, 23, posted a Games record of 2:07.24 seconds to beat compatriot Emily Seebohm in the women’s 200m backstroke.
Then James Magnussen edged out team-mates Cameron McEvoy and Tommaso D’Orsogna in the 100m freestyle.