I guess only Granada TV could answer the question. The series was, as far as I am aware, only made in good old monochrome. Few DVD releases are available of that vintage and especially if they are not in colour. You can sometimes find old series on DVD around on the net (I recently managed to obtain the old Terence Morgan Sir Francis Drake series) but it would be great to see the young Thaw and Bolam again in what was a wonderful series with (as I remember) a great theme tune.