I really cannot see the benefit of HS2 to the airport. There are already five trains an hour to London and three of which take about 75minutes to Euston.Fares are also very reasonable if you pre book. I cannot see a slighly quicker journey making any difference to catchment. I would like to see a twenty four hour service though, even if it was a slow train. The problem at the London end is Euston as the underground is not really equipped for anybody with significant amounts of baggage.I have seen no mention of enlarging the Euston underground station in any of the plans for the HS1 terminal. I would personally build a new station adjacent to Kings Cross/ St Pancras for HS2 so that it links to Thameslink, and HS1 and the Eurostar.