There is nothing new in this - it has all be said and answered before.
Working on the train: A sick joke on the trains I use, they are too crowded and even when not full the seating designed for high desnity occupation makes using a laptop impossible. This will only get worse as trains become more crowded. The OXERA report to the Transport Select Committee quoted studies that had found working on trains to be about 20% as productive as office work. And the arguiment cuts both ways - if you think that people can work effectively on trains, then you must accept that increased productivity from reducing crowding and capturing traffic from road is a benefit of HS2.
Growth forecasts - these are actually very conservative, and well below the levels we are actually seeing now and have seen for 15 years.
The comparison with HS1 (I think they actually mean Eurostar here) is not valid. The passenger forecasts were made by a bidder to build the rail link and operate Eurostar trains - we have a competitive tendering process designed to ensure that to win you must be optimistic, if you don't inflate the figures you don't win. The actual high speed element introduced in 2007 with completion of HS1 through to London has clearly boosted Eurostar traffic, its problem is that it is a percentage increase of a low base. The new competition that Eurostar faced was a step-change resulting from development of low-cost airlines, which quite out of the bounds of a relatively well-understood rail market. The forecasts for HS2 did assume a level of service on the classic routes. There is a large base of rail traffic already so that the uncertainty in forecasting is much less than for Eusrostar or the South Eastern high speed services, both of which were largely aimed at markets that were new to rail.
Distribution from Euston - HS2 is the only project that actually has a means of diverting passengers away from Euston by allowing them to change onto Crossrail at Old Oak Common. The traffic is coming one way or another - it is doing nothing or implementing RP2 and its suggested variants that pushes all WCML passengers into Euston. TfL accept that Phase 1 of HS2 does not call for additional tube capacity from Euston, whilst for Phase 2 what they are after is diverting the already planned and justified Crossrail 2 through Euston, very sensible, and the additional cost attributable to HS2 is virtually nil.
Conventional alternatives - the IEA seems to be saying that its solution to rail crowding is to price people off. So-called incremental investments cannot cope with even the most basic forecasts of growth let alone the actual levels of demand increase that we are actually experiencing (for a full analysis see
www.williambarter.co.uk/pdf/RP2%20cannot...kground%20growth.pdf). Those who say they can are depending on sexy eye-catching headline figures for load factors and capacity increases generated on the thoroughly false basis of adding capacity at times of day when it is not needed, ignoring 1st Class which does fill in the peaks, and comparing with forecasts made in 2007/8 which have been exceeded by a factor of 2 or 3 in each year since then.