Ian - can this be quantified or is there a link to a data source. 'Awash' is such a vague and non-specific term to an aviation or airport analyst that it would be helpful to get some hard data to support it.
The other thing to remember in this debate is that the whole concept of acceptable overland travel times is completely different depending on your cultural background and what is normal in day to day life. The average US, Indian or Chinese citizen for example would find 2 hours on the train from London as 'round the corner' by their own standards and on that basis London, with it's obvious draws, becomes a very well placed base to explore the rest of the UK. Many travel itineraries from the US and the Far East also tend to be European focussed. A tour of European capitals with an extended stay in London is quite common.