Stop me if you think you’ve heard this one before. The Prime Minister’s claim about Sir Keir Starmer is gutter politics, but the genie will not so easily go back in the bottle.
The facts are Sir Keir was the director of public prosecutions from 2008 to 2013, leading the Crown Prosecution Service (CPS).
However, the Labour leader played no role in the decision not to prosecute Savile, but did as head of the CPS apologise on behalf of the organisation.
We know this. The Prime Minister knows this, but having said it Downing Street can now only insist his point was misconstrued, while at the same time his own MPs go back and repeat it.
One defence issued is the issue is brought up on the doorstep, but this is not a defence. It simply means Mr Johnson has heard a falsehood and repeated it.
And now his own ministers repeat it or claim the concerns were valid, as if apologising for something you had no direct involvement in isn’t quintessentially British.
Those who do speak out are met with derision or accusations of treachery.
Asked at a Downing Street press conference about the smear, Chancellor Rishi Sunak replied “being honest, I wouldn't have said it”.
The comment sparked fury among the Cabinet, with ministers briefing Mr Sunak had betrayed the Prime Minister, or made a blatant move on the leadership.
In reality he had said the absolute bare minimum, ruling out making the smear without condemning it.
An intervention by the Speaker is significant, but the smear is now part of the discourse.
For as long as conspiracy theorists endanger the Labour leader outside Parliament, or Mr Johnson refuses to apologise, MPs will keep being asked about it.
And we know he won’t apologise. The Prime Minister previously dismissed fears his use of language such as “traitor” and “betrayal” was dangerous as “humbug”.
Mr Johnson will not say sorry or admit he got it wrong, so ministers will continue to defend the indefensible.