Britains love affair with interior design and home improvements has been highlighted by the runaway success of a TV design show. Channel 4s interior design show Grand Designs has proved a massive ratings hit in its second series, this week claiming an additional 700,000 viewers and cementing its Wednesday night supremacy.The show, presented by Kevin McCloud, covers unusual house-building projects such as underground homes and its popularity has revealed a public enthusiasm for kitchen design and other DIY adventures.This weeks viewer bonanza took the shows audience to 4.7 million, making it one of the most watched programmes in the 9pm slot.And Channel 4 also revealed a kitchen-related success, with celebrity chef Gordon Ramsay picking up promising ratings for his latest cooking programme.Ramsays Kitchen Nightmares USA, in the 10pm slot, garnered 3.4 million and a 19 per cent share, affirming the newfound British passion for sinks, chopping boards, ovens and kitchen debacles.