Should you wish to fly from Edinburgh to London, you are spoilt for choice – and low fares. Ryanair is currently selling its morning flight from the Scottish capital to Stansted for £17 one way – a fare that helps explain why rail firms have not captured the entire London-Edinburgh route from planes. The cheapest easyJet can offer is £19 to Luton; to Gatwick, you will have to fork out all of £30. On British Airways, the sophisticated service and generous cabin-baggage allowance aboard the BA