Parliament has always been a source of colorful language, but this week the tone darkened

Rules on parliamentary language which prevent them from using straightforward epithets like ‘liar’ force MPs into ever more inventive invective

Johnson addresses MPs in the House of Commons on Wednesday (EPA)

The House of Commons is not for the thin-skinned or the faint of heart.

Not for nothing is the chamber known as a bear pit. When passions run high, insults are hurled between the green benches and angry MPs’ tongues often run away from them until they have to be reined in by Speaker John Bercow’s famous cry of: “Order! Order!”

Rules on parliamentary language which prevent them from using straightforward epithets like “liar” force MPs into ever more inventive invective, and the Commons has seen honourable members denounced as “a semi-house-trained polecat” (Michael Foot on Norman Tebbit) or “a pig’s bladder on a stick” (Tony Banks on Tory MP Terry Dicks).