Weatherlawyer presented the following explanation :
Red is the equivalent of Brown and Black is now Blue. Earth was a plain
green and is now green and yellow.

Apart from the fact that it would be unlikely to have been wired with
an earth, those which were provided with one were just bare copper
wire.

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Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk