Polly Filla is not Polly Toynbee, you crazy, wild thing!
It's a composite of a certain type of columnist. I think it was Peter Cook who said it was a send-up of 'the sort of columnist whose writing is like the crowing gossip of a particularly unpleasant woman, across the garden fence.'
Jean Rook once famously accepted the accolade of it being based on her and highlighted the misogyny.
Lots to unpack re the misogyny bit.
But ... Polly Toynbee? No. She's a political columnist and far more easily parodied as a patrician philanthropist in the late Edwardian style.