Sounds like a dreaded Leylandii!!! They grow 'for England'. As it's blocking light from a street lamp, have a word with the local council, (overhanging tree's). They will write to the occupier and ask for it to be cut back. If the occupier doesn't comply (think it's 2-3weeks) phone the council again. They may get the job done and then pass on the bill to occupier.
You do have the right to cut branches overhanging your garden off, but you must return then to the owner of the tree!!
Have a look at www.gardenlaw.co.uk.
It gives more detail than space allows here, and scrolling down the page there a lots of useful links/info
Good luck