Out of interest, why did your mum think Benn wasn't a nice man, despite liking his politics?
For me, I'm not sure that I'd describe him as "not a nice man"; rather, that there were some aspects of his personality and actions that were questionable.
For example, why would he insist that his "Who's who" entry not say that he was educated at Westminster? Why would he announce on the BBC that henceforth we wanted to be known as "Tony Benn", not "Anthony Wedgewood Benn"?
It's one thing to have totally different politics to the norm for your background and to proclaim your politics loudly. It's quite another to try to erase your background from public consciousness.