A taste of the high life

It could be worth bearing these words from section 39 of the National Rail Conditions of Carriage [in Great Britain] in mind, should you find yourself in a packed train, perish the thought:

If you have a standard class ticket (other than a Season Ticket), no standard class accommodation is available, and ticket staff on that train give their permission, then you may travel in first class accommodation (or the equivalent) where this is available without extra charge.

On-train ticket staff will not give you permission to use first class accommodation (or the equivalent) unless they are satisfied that it is not required by anyone with a first class ticket and the standard class accommodation on the train is full. This permission may be withdrawn if a person holding a first class ticket requires the accommodation during your journey or standard class accommodation becomes available.

Source: http://www.virgintrainsfares.co.uk/button_bar_pages/national.asp

The National Rail web site does not currently appear to publish the NRCC in html format: see http://www.nationalrail.co.uk/times_fares/nrcc/
for the first page only and a PDF download.