As I understand it, North British never made any adequate investment in the precision tools or workforce training necessary to make diesel locos, transmissions, or the various accessories that go on one. The only established builder that seemed to understand the new market was English Electric, who had been doing them, for export, for some time, and who had substantial experience with high precision aircraft manufacture by the time their diesels came along. There were even more substantial failures by the UK builders with diesels in their export markets than for BR.
This sort of mirrored the USA experience, where the three traditional main steam builders floundered with diesels, despite all trying. Alco made a go of things for a while, but were eventually defeated, Baldwin, one-time largest US builder, "did a North British", and produced poor designs which were generally the first to be withdrawn, while Lima hardly got started before giving up.
) they always seemed to missing the odd solebar panel and generally looking a bit rough...
