Have just been to seek advise from the leccy at work.

He said. If you have a seperate switch also for them then you can just replace the light fittings. However, if you don't then you need to wire a switch in.

Hope this helps.

Wire in a clapper

Well OK.....

Definitely not neccesary if you can operate your existing lights through a wall switch as well as the pull string.

The power is going from the loop to the lights via the switch. The switch on the existing fitting is essentially a circuit breaker at the point of the light, if that switch wasn't there then the power would go direct to the bulb.

If you can only switch them on and off via the string then its a whole different job.

why dont you get in touch with Part P a suitably qualified professional electrician for advice

i fully concur with Mr I
if you can switch the lights from a separate switch then you do not have a problem.....and like the good man says ...its a different ball game if not......