I think they are arguing that New Labour took its 'traditional vote' for granted and that the party is currently paying the price for that. See below for what Mandelson allegedly said, for instance:
I think this is an issue the tories will have with their traditional base in time as well - some signs of that in the elections (poor results in affluent south east like Tunbridge Wells).
In policy terms though, what did new labour do that abandoned those people?
I think they are arguing that New Labour took its 'traditional vote' for granted and that the party is currently paying the price for that. See below for what Mandelson allegedly said, for instance: