There was outrage at Westminster on Wednesday when the Prime Minister accused Keir Starmer of condoning support for the IRA.
In a row at the despatch box Boris Johnson accused the Labour leader of serving in Jeremy Corbyn's Shadow Cabinet despite his support for the IRA.
It was a comment which came out of nowhere after Starmer had the PM on the ropes over the exams grading fiasco.
Bang to rights on the subject, which led to a Government U-turn to appease thousands of angry students, Johnson dived straight into the gutter.
Not only did the Prime Minister attempt to tie Starmer to condoning the IRA, he also cited the anti-semitism crisis that plagued Corbyn's time as leader and Starmer's support for remaining in the European Union.
Starmer was quite rightly furious at the Prime Minister's dog-whistling attempt to mislead the public on his views.
If this is how the Prime Minister responds to legitimate criticism he could be in for a difficult few years at the despatch box.
One wonders if he would have been so quick to smear Starmer without the benefit of Parliamentary privilege.
While the Corbyn leadership regime undoubtedly had its issues, he always denied ever supporting the IRA, to attempt to blame Starmer for the sins of the father is disingenuous in the extreme.
Starmer went on record in 2017, while serving in the Shadow Cabinet, saying he found Mr Corbyn's associations with the IRA "regrettable".
That is not to mention the time he spent working as human rights advisor to the Northern Ireland Policing Board and his role in prosecuting terrorists as Director of Public Prosecutions during a lengthy legal career.
The Prime Minister's comments were little more than cheap political point scoring during a difficult spell for his Government.
In response to Johnson's comments Starmer immediately called for a retraction, with the PM suggesting his protests might have been better used during Corbyn's time as Labour leader.
"I asked him to do the decent thing, but doing the decent thing and this Prime Minister don't go together," Starmer said.
Some have dismissed the Prime Minister's words as "watery" or "handbags" at the despatch box.
But there are over 1,500 families with empty seats at their tables as a direct result of the IRA.
The group's terror campaign leaves many open wounds in Northern Ireland and that the PM would invoke them so flippantly shows a level of detachment to the real hurt still felt by many.
The rest of the UK was not untouched by IRA violence - something which we were reminded of this week.
Tuesday would have been the 40th birthday of Tim Parry.
Tim (12) was killed alongside three-year-old Johnathan Ball when the IRA planted a bomb outside a shopping centre in Warrington in March 1993.
I wonder how the family would have felt hearing the PM use their son's killers during a petty squabble in the Commons in what must have been a heart-wrenching week.
"The light that always shone from Tim's eyes was extinguished that day and there was a void that nothing would, or could, ever fill," dad Colin said.
The Prime Minister should know better.