Colney Hatch

Colney Hatch was the name of an insane asylum in London.

History
The asylum opened in 1851, and was the largest asylum in Europe at the time.

By the 1880's, public perception of Colney Hatch and its patients caused the words "Colney Hatch" to be used to refer to anything unusual or irrational.

One such example was the scene involving Jadis, the former Empress of Charn, when she declared herself Empress, in The Magician's Nephew.

The Fight at the Lamp-post
Shortly after Jadis arrived on Earth, she caused a scene by stealing some jewelry and a horse. When she was stopped in the street, she loudly declared who she was, only to be ridiculed by the crowd: -

"Three cheers for the Hempress of Colney 'Atch!"

- a member of the crowd at the lamp-post, mocking Jadis

Jadis was infuriated by this comment and the Londoners' inability to take her seriously. In response, she hit the chief policeman on the head with a bar that she had broken off from a lamp-post, and threatened to destroy the whole city. Digory and Polly, however, used their magic rings to take the witch back to the Wood Between the Worlds before any real damage was done.