Rex Restaurants is planning its third London opening in less than a year in September. The company will open Cafe Colbert in Sloane Square on the site of the former Oriel restaurant. Colbert will be in the tradition of St Germain brasserie cafes. Rex Restaurants opened Brasserie Zedel off Piccadilly a few months ago and The Delauney just before Christmas 2011. A luxury hotel is planned for Mayfair’s Balderton Street in 2014.