Prime minister's questions sketch
By Nick Assinder
Political correspondent, BBC News website
It may have been on a slow fuse, but finally this Brown-Cameron clash erupted into fireworks.
And not just because Labour's Brian Donohoe risked killjoy jibes by calling for a fresh ban on the explosives.
Mr Cameron was accused of misleading MPs
On this occasion it was the row over the report into the chaos surrounding last May's Scottish elections that lit up the chamber as sky rockets, bangers and Vesuviuses (or is that Vesuvii) all went off at once.
David Cameron pointed to a section of the report into the affair which suggested party political considerations had been placed ahead of voters' interests by the man who ran the farce - minister Douglas Alexander.
Mr Brown chose another section which insisted no one party was to blame. Both were right.
Still, it rumbled on nicely, spitting the occasional mushroom cloud of multi-coloured sparks - until Mr Brown accused the opposition leader of "misleading" the House.
And you just don't do that in the Commons which is, as we know, entirely populated by honourable men and women.
The remark threw a lighted match into the entire box of fireworks with the inevitable and hugely entertaining results.
Mr Martin had to call for temperate language
It brought a rebuke from the Speaker, who demanded "temperate language" and Mr Cameron, who had by now worked himself up into what looked like genuine affront at Mr Brown's denials, exploded to a chorus of traditional "oohs" and "aahs".
"I do not know how he has the gall to accuse me of misleading people," he declared, pointing to page 17 of the report which talked of party interest in the ministerial decision-making.
Mr Alexander, he said, should be hauled before the Commons to apologise and be stripped of his responsibility for election planning.
Is this the new politics Gordon Brown had promised in his leadership manifesto 100 days ago, he said.
"Does that not feel like 100 years ago?" he added as the final, surprise explosion at the end of the cascade.
Mr Brown did his own quoting from the report but ended with a bit of a phut rather than a bang - pointing out once again the report had not blamed one political party, but all.
He was right, but it somehow didn't quite light up the sky.
In the middle of all this, like the jacket potato in the centre of the bonfire, Speaker Michael Martin popped.
And, for the second week running, it was Gordon Brown's bag carrier Ian Austin - who has a habit of standing by the Speaker's chair yelling abuse at the Tories - who got the flying ember in the neck.
"The best thing for you is to stay away from my chair because my hearing is bang on. Right," said the Speaker with more than a hint of menace.
That was a rocket and no mistake.