The first new Piccadilly line trains have entered testing – and are due to start running in London in two years.Transport for London bosses say the 94 new trains will transform one of the Tube’s busiest lines, increasing capacity by 10 per cent. They will also be the first deep-level “walk through” trains on the Underground - and the first with air conditioning.A new moquette seat pattern has been designed for the trains, named Holden in honour of Charles Holden, the London Underground architect between the 1920s and 1940s who changed the face of the capital with iconic stations such as Arnos Grove and Southgate.