Until 1998, a point of order during a vote in the House of Commons could only be made while wearing a hat.
— Ned Donovan | فارس دونوفان (@Ned_Donovan) January 17, 2023
A collapsible opera top hat was kept with the doormen solely for this purpose, as seen worn by Tony Marlow in this clip from 1994. pic.twitter.com/evVm033phH
In its modern form, the British House of Commons dates back to 1801, although its origins can be traced to 1341. That's several centuries of developing tradition, including the rule that, if a member wishes to raise a point of order to the Speaker, s/he must be "seated and covered" -- the latter of which means wearing a hat of some sort.
Since headwear was in decline during the late Twentieth Century, it became customary to keep a single collapsable opera hat nearby. The member must retrieve it and then sit down before raising the point of order. One advantage of this practice is that it has:
...has undoubtedly been retained to deter honourable Members from raising points of order during divisions by making them appear ridiculous and feel acutely embarrassed.
This noble tradition was eliminiated in 1998.
-via Marilyn Terrell