Cost effective travel

With all the 'journalistic hype' that has been written about Cameron's jaunt to meet Obama there is one aspect which I do not seem to have read about.
We can, no doubt, assume (hopefully) that the media 'footed the bill' for their correspondents who covered this jaunt - their air fares, hotel bills, food etc; but this then leaves the bill for Cameron, his wife; his political 'entourage'; plus probably Sam's hairdresser and her 'assistants'.
As this country does not possess a 'Camerforce One', this jaunt was either undertaken on a scheduled flight or one chartered. Which? It can be assumed that if a scheduled flight, then Cameron et entourage did not travel economy or business class. In which case how much of the first class accommodation was booked and who for? If a chartered flight, the same questions arise.
We are told that all travel is based on the most cost effective method - however, that raises yet another question, namely cost effective for those involved or cost effective for the taxpayer who funded this jaunt?
Of course if we had the 'Referism' element of direct democracy Cameron would have had to seek prior approval from us for the expenditure involved - to which I would suggest the answer that should have been given was: "You keep informing us you are one of those who can walk on water - prove it!"