Lighting - Legal/Planning Question

[andy20]

I have a relative who lives upstairs in a flat and has an apparently inconsiderate neighbour living downstairs who decided to erect an olde-style lantern (3m-ish in height) in the back garden which is left on all night and shines directly into the upstairs windows.

Obviously not happy about this.

Any idea what, if any, laws/regulations are being broken? (ie. any idea if planning permission is needed?)

Cheers.