We're getting the Eurostar tomorrow morning. We (2 adults, a 5yo and a 3yo in a pushchair, with one large suitcase) need to get from Marylebone to King's Cross. Is it madness to attempt to do this on the Underground? We're happy to carry the pushchair, but I'm not sure this is allowed on escalators and I know some stations have a lot of steps. Has anyone done this journey and/ or can advise?