Socio-economic class of UK passengers has not changed over time

Work by Jeremy Birch, from the Stop Bristol Airport Expansion (SBAE) campaign,
shows clearly that the fraction of passengers in each socio-economic group has
stayed almost constant since 1996, and there certainly has not been an increase
in the fraction of poorer people flying. As the total number flying has increased,
this means that the poorer people do fly more than before, but there is no progressive
element here.  Jeremy’s study used CAA passenger data from 1996 onwards.
The details are at  
Social Class of air passengers unchanged