To de harmonise the black from neutral from old colours I believe
London, Would you care to shed some light on that satement.
We don't know what colours have been used at the DB end.
That is a fair statement. We know that the protocol now is to oversleeve grey with blue and black with green/yellow, but that is not always adhered to (or strictly necessary), so we can't really advise anyone of colours to use at one end without knowing the other.