I see where your going with the 3 Core + Earth suggestion.
However in my situation the ceiling rose sits directly underneath the part of the kitchen with a flat roof meaning the only way to run new cable between the switch & rose would mean cutting a path into the ceiling then having to get it replastered afterwards.
Whereas the 1G switch sits under a section of the roof which is pitched. and easily accessed from the loft by moving aside some insulation.
The plan would be to have the wire fed down through the stud wall straight into the mounting box using the current wire as a guide, and if all goes to plan foregoing any damage to the plaster.
The live feed to the ceiling rose passes right next to where the switch cable goes down into the stud wall. So seems the ideal location to junction from.
From there I can plan a route down to the cabinet which minimises the damage which I should be able to fill over easily enough once electrician has finished.
My main concern was regarding the need to chase out an additional FCU which you have explained should not be necessary.
Am I right in thinking that you didn't have a problem with the junction box method you just thought the 3 core + earth solution was a more elegant one?
I would be discussing all this with the electrician but I missed his deadline so he wont be back until November.
So thanks for the assistance.