Replacement exterior light

[scotbruce]

Hi
In our 1935 house, I have two outside lights, one of which stopped working. When I tried to change the bulb, I found the fitting was broken.
A replacement bulkhead light requires an earth, but both of the existing fittings have only live and neutral (black and red), with no earth and none visible (or cut short).
The double light switch is immediately inside the front door, with one for the two exterior lights and one for the inside hall light.
There is an earth wire within the light switch, but (inside the adjacent small access hatch in the thick granite wall) there are only two cables, sheathed in black rubber, running up towards the top of the door and then presumably outside (and none running elsewhere).
Is the only solution to replace the existing cabling with twin and earth?
Thanks in advance for any help!

 

[EFLImpudence]

Is the only solution to replace the existing cabling with twin and earth?

Not necessarily with T+E.

If it goes outside, rubber flex is more suitable.

 

[PrenticeBoyofDerry]

The fitting requires an earth/CPC, so you need to install on and prove continuity of it's path back to earth.

Twin & Earth is not ideally suitable for cable that is exposed to the outside environment, so either a cable/flex should be selected that is or the external cable should be contained within conduit.

If you are removing the old cable, investigate how the circuit is configured and how the live/line and neutral are arranged, don't be fooled into believing the conductor core colours are if black always neutral!