Best way to run a single neutral in a domestic property?

[LlandrilloSpark]

Guys

I've come accross A borrowed neutral in the upstairs/downstairs lighting circuits in a property where I'm fitting a nw dual rcd board.
It's the usual landing light job, feed from downstairs circuit, Neutral borrowed from upstairs circuit, I need to run a seperate neutral from the landing light rose to the loop in terminal in the downstairs hall light, the run starts in the attic then goes through a disused airing cupboard then under the floor, I'm going to run a single 1.5mm, even though it's technically hidden everywhere what do you all think is the best way to run or protect it, I was thinking mini trunking or oval conduit?
Cheers

 

[Andyfm]

As long as its double insulated, I can`t see a problem

 

[Hawk81]

is the earth also taken from the upstairs lighting circuit to the landing light. if it is i would run a neutral and earth from downstairs to landing light. and then both circuits will be completely separate.

 

[Mr Mark Sparks]

yeah i agree t&e with the brown cut out/made safe

 

[telectrix]

or feed a live and earth from uptairs and dis the existing live

 

[LlandrilloSpark]

Landing light ceiling rose contained single double insulated neutral and a two core red for switched line and earth which comes from the switch which is fed from downstairs, so I presuming it's earth is on downstairs already, I suppose I could make sure by using the brown cut out method and running a neutral and earth to downstairs

 

[nickblake]

Me mate id use 1.5mm and connect up the cpc and the neutral and not connect the live

 

[LlandrilloSpark]

Looks like I will be taking the 1.5mm single back to C.E.F then!, I will go the T&E route