Sorry to be a bringer of doom but I guess you have a house from the 70’s because they did not use a earth then
but alas since the 15th edition of the wiring regs all lighting MUST have a earth, why you ask well it is a safty circuit and no electrician worth his title will not touch your lighting circuit and if you had your house tested it would fail the Z’s test and be condemed
Just get it rewired for your own safty and that of your family
Sorry to sound mellow dramatic but because you posted on here you do not know what you are doing ( as are alot of the above posters) please do not become a statistic get someone in