The chef, who has worked at London's Bluebird Club and the Café Royal, has exchanged on the lease for the former Smollensky's Metro in south Croydon for an undisclosed sum.
The menu of fresh fish sourced from Brighton, Eastbourne and Cornwall will range in price from around £5 for poached eggs with haddock to £20 for Dover sole.
Grill items will include rare breed lamb and 28-day hung Aberdeen Angus, as well as burgers. Organic bread will come from the Born and Bread bakery in Dulwich, south-east London.
Fish & Grill will feature wooden tables with no tablecloths, oak floors, exposed brickwork, high back seats and leather banquettes. There will also be a shellfish display and a range of draught beers thanks to a large cellar.
John told Caterersearch: "Croydon has moved on in leaps and bounds in recent times and despite the downturn caused by the credit crunch I'm confident there's a market for a good grill restaurant."
The restaurant, which will also have outside seating, will be looked after by a team of 14 with John spending the majority of his time in the kitchen throughout December.
By Chris Druce
E-mail your comments to Chris Druce here.
Looking for a new job? Find your next restaurant job here with Caterersearch.com jobs