I have to fit a new kitchen light which has an earth. However the light I am taking down was not earthed and there is no earth wire in the ceiling wiring to connect to the new fitting. Can I just connect to live and neutral cables?
that will make the light work, but the problem is you don't have an earth connection. I'd be checking your electrical installation to determine if this is just on this light or the whole system.
It's dangerous if you don't have earth protection installed.
This must be checked!
Remember be safe!
Years ago we did not use earths on light fitting and still a standard ceiling pendent with single bulb is what we call double insulated and has two squares one inside another. I can't remember when we started including an earth wire to the rose but a long time ago and now there is normally an earth screw in every rose. Either you must continue to use simple bulb or re-wire.
Although you may find a local earth the regulations say it must follow the same route as the supply cables so it would be silly to add latter just as easy to renew cables.
When we find no earth on lights it rings alarm bells, Although everything may be OK you may also still have rubber cables which by now may be perishing. You should have your system checked every ten years or change in occupants but this is only really done in rented property where insurance would not allow a Land Lord to get away without a re-test.
Your wiring may of course be OK but it would be wrong not to point out that you may be better getting it inspected and tested.
No! If fitting has an earth connection then it must be metal and therefore MUST be earthed, change fitting for a class 11 fitting  double insulated or have lighting circuit rewired as it must be at least 35 years old.
Unless your wiring is really old, the light rose is likely to be fed by twin and earth pvc cable. The earth wire is bare and was previously unused. Hence many electricians simply cut it off rather than sleeve it and connect it to a spare terminal in the rose.
If there is enough slack you may be able to pull the cable out a few inches, strip the cable sheathing back and thereby regain the earth wire.
However, this does not necessarlilly mean the earth is connected at the fuse board, or in any intermediate junction boxes. You will need to verify this to ensure electrival safety and comply with the current regulations. All metal fittings must be earthed. Call in a professional if in any doubt.