Blair’s policies, supported by the Parliamentary Conservative Party, and despite a large-scale rebellion by Labour MPs, did to the Middle East, IIRC.

Blair only got support from the Conservatives because he lied to Parliament.
He stated that he had seen conclusive proof that there were WMDs capable of rapid deployment against the UK. Proof which, he was unable to share with Parliament!

Compared to which, Boris' confusion over exactly what constituted a party, and what was a workplace event seems negligible.