Among the smart suburban homes of Twickenham is a very strange house.  Gleaming white walls, battlements, Gothic pinnacles and a round tower stand out against more restrained neighbours. Strawberry Hill House, home of the eccentric man of letters Horace Walpole during the second half of the 18th Century, is arguably the birthplace not only of the Gothic revival, but also of the Gothic novel.   I visited Strawberry Hill on a very gloomy Saturday afternoon, which didn’t really do the house’s bright white walls justice, but the house had only reopened a few weeks earlier after an extensive restoration and despite the grey weather the house was clean and jewel-bright – and quite possibly one of the oddest homes I’ve ever visited.