Marks & Spencer was given the all-clear to demolish its 94-year-old flagship store at Marble Arch on Thursday ending one of the most bitterly contested and high-profile planning rows of recent years.The retailer wants to knock down 1930s Orchard House on Oxford Street, as well as two other more recent buildings, and replace them with a ten-storey development with a new but smaller M&S store, a pedestrian arcade, offices, a cafe and a gym.