The Bledlows are the policemen of the Unseen
University. They are mostly former watchmen and soldiers, heavy-set and have quite a good turn of speed for their age. Like watchmen everywhere, they believe in the
universal guilt of everybody -- in their case, the students.
They have a time-honoured and arcane ceremony at two
in the morning which is akin to the Changing of the Guards in other cities of the Multiverse, only louder and more obtrusive, involving the Patting of the Pockets, the I'll Swear They Were Here This Morning, and the Stone Me, They Were Here All Along, and ending with the signing-over of keys between the incoming and outgoing porters. Attempts to get them to turn the volume down a bit are regarded as gross insults from people, who while they might know the value of a
good night's sleep, have no respect for deeper values such as Tradition.
In The Last Hero and the The Science of Discworld series, the Bledlows are used by Ridcully to prevent Rincewind from
running away. (When confronted by a potential act of heroism, Rincewind follows his better instincts by turning and running.} He doesn't get very far before being (gently) restrained by grinning Bledlows, who are noteworthy in that they have succeeded where other, younger, guards with more weapons and attitude have failed. They are, in short, the one body of men whom Rincewind cannot outrun or evade, which says a lot for all the practice they get chasing down students.
The one person they have thus far been unable to restrain is Granny Weatherwax, as demonstrated in Equal Rites. When Granny really wants to
get into the Great Hall and see the Archchancellor, nothing (
not even Bledlows) is going to be able to stop her.