If you want to comply with Chapter 514 & Appendix 7 of BS7671....
then probably no... especially on new additions & alterations..
I suppose it could be argued on a like-4-like cable fault repair of an existing installation, keeping old colours constant through the installation is no less safe than changing colours at two points along a run? :innocent
It could also be argued that you are being more environmentally considerate using up old cable.....
ray
But as 31 March 2006 was the official cutoff date for still installing old colours..
It could also be argued that the cable is old and may have been damaged lying around somewhere? :|
However an existing installation can have older cables already fitted that are still safe!
Bottom line is officially it would not comply!
personally I would not recommend anybody does install any...
But if you were going to..
you may want to thoroughly test the cable before it is installed to check it isn't nicked, squashed, damaged etc..
:|