A new Sainsbury’s supermarket at Shenley Church End will be open by this time next year, creating 110 new jobs for local people.
Builders started work this week on the site, which once housed Dolphin Splashdown swimming pool.
A residents’ campaign to restore the pool for community use failed earlier this year when councillors granted planning permission for the 2,000 square metre store.
A Facebook group called Save Dolphin splashdown gathered 2,418 likes. Dozens of people also wrote to city planning officers urging them to save the building a restore the pool.
But the restoration cost was estimated to be around £2.6 million and planning councillors voted in favour of the Sainsbury’s application.
The building has now been fully demolished and the site cleared ready for foundations to be laid.
A spokesman for the Save Dolphin Splashdown campaign said: “It’s not what we wanted and it’s a great shame.
“We still think the community would have enjoyed a purpose-built swimming pool more than yet another supermarket.”
Sainsbury’s already have a convenience store metres away at the Shenley Church End local centre. The company has promised the new development will “safeguard” the jobs of the 30 employees working at the smaller store.
Tim Watkins, Sainsbury’s regional development executive, said: “It is exciting that work is starting on the construction of our new store. Once complete the store will offer a fantastic new shopping opportunity for customers.”
Builders GF Tomlinson and Sons aim to complete the development by spring next year.
The store will then be handed to Sainsbury’s for internal works to be carried out in readiness for a summer opening.