jgharston wrote:
ARWadsworth wrote:
What you have here is the standard method of converting a one way
switched light into a two way.

Standard in what way?

It's /a/ standard method:
http://www.diyhowto.co.uk/projects/two-way-lighting.htm I prefer to
avoid it unless I have can't, as having five wires
coming out of the switchplate backbox can confuse future
maintainers, even more than a loop-in ceiling rose can.


It is not a standard method that the OP referred to and gave a diagram for.
His concern was not the 3 core and earth cable used for the two way
switching but the three core and earth cable used for the switched drop that
used one core for permanent live and two different switched lives on the
other cores.

Read the OPs question and not Harrys waffle.

--
Adam