British independent production company Boom Pictures will back Laura Mackie and Sally Haynes’ new drama shingle, which is to be called MainStreet Pictures. The ITV executives, who are responsible for getting Downton Abbey on the air, announced last week that they were leaving the network to set up their own indie. MainStreet will launch in July as part of the Boom Pictures stable of companies which also includes TV producers Boomerang, Apollo and Delightful Industries, post-production outfit Gorilla, talent agency Harlequin and documentary producer Indus Films. Former BBC One controller Lorraine Heggessey is Boom’s executive chair with whom Mackie and Haynes worked at the BBC prior to their seven-year run at ITV. Most recently at ITV, the duo commissioned series Appropriate Adult, Mr Selfridge and Broadchurch, which was acquired by BBC America earlier this month. MainStreet will operate from Boom’s London offices.