Eurostar plans to introduce double-decker trains through the Channel Tunnel, ordering up to 50 trains from Alstom. This expansion includes significant investment in a London depot, raising concerns about space for rival operators. The €2bn deal includes 30 'Celestia' trains, potentially increasing passenger capacity to 30 million from 19.5 million. The new trains aim to enhance service frequency and comfort, while Eurostar faces competition from new entrants in the cross-Channel rail market.