The “determined effort in both the British media and the wider political elite to delegitimise the Labour leadership in particular and the broader left as a whole” is a strategy that I hope most people can see through.
Aggressively attacking someone while simultaneously framing themselves as the victims of an attack is a sign of desperation. It frames a reasonable point of view into an act of mindless aggression. We should stop engaging in these tactics. We need to find ways to reframe the issues. What the right manages to do is turn reasonable intelligent debate into emotional outpourings. They appeal to the gut not to the head. They appeal to emotion and not intellect. The left has to find ways to engage with the wider world on an emotional level without sinking into the spite of the right. If they don’t the conversation will end up being something akin to the vitriolic exchanges of an acrimonious divorce.