Brighton Aquarium or the Brighton Sealife Centre is the oldest operating aquarium in the world. It opened in 1874 and still exhibits some remarkable victorian architecture.
Am indoor dolphinarium was completed on the easter of 1968/opening easter 1969? and the dolphins instantly became the most popular attraction at the aquarium. Aswell as the dolphins the aquarium also housed sealions, seals, penguins and a baby crocodile. (Rocky, a sealion who had be born at the aquarium passed away at the national seal sanctuary on april1st 2009. He was moved from the aquarium after developing cataracts in both his eyes when he reached 5 months, and so was untrainable. RIP Rocky.)

Two of the resident dolphins were called Missy and Silver, but at one point there were 5 dolphins in the pool (which remains today as the turtle/shark pool with a glass walkway through it. The tiered seating for the shows is still there. (can anyone confirm whether they are from the dolphin era or not?) On their birthdays, children had the opportunity to ride in a little boat on the pool and the dolphins would "sing" happy birthday to them. There was a sealion called Fred, and two seals named Yogi and Sunshine. Protestors and the new laws for marine mammal keeping (1993) lead to the closure of the marine mammal exhibits.
The main dolphin show pool:





The original dolphin pool, which then housed the sealions:


The sealions:

For more information on ex-employee's experiences: