There is no family silver left, Thatcher and Blair sold it all. The only thing they can do is throw as much money as possible at rich people in the time they have left, secure in the knowledge that Starmer’s Labour will keep their seats warm without doing anything at all to stop the theft.
It’s a term that originates with the left. Specifically, those who broke with the USSR over imperialist invasions, referring to those who did not. More broadly, it refers to the authoritarian left (as opposed to the anarchist left).