Algodoo

All five locomotives were withdrawn on 30 December 1967. By this time they were non-standard, even for hydraulic designs, although according to Laira staff reliability was not a problem as many have thought. BR had been ordered to reduce the number of mainline locomotive classes from 28 to 15 by 1974, primarily by eliminating types which were known to be unreliable, had high maintenance costs or were so few in number as to be non-standard. As the table below shows, there was a substantial gap between delivery of D601 and D602 because NBL had to equip itself to construct the engines and transmissions for these three locomotives. By then the first Swindon-built D800s (later Class 42) had entered service, these being the lightweight and more powerful diesel-hydraulic locomotives they had requested.

D600 and D601 were sold to Woodham Brothers scrapyard in Barry, South Wales. D600 was broken up within a couple of years but D601 remained intact until 1980. Preservation for D601 was denied on the ground that it was too far gone to be restored to operational condition and was not considered to be worth preserving for display only. The last Class 41 unit was broken up at Barry Scrapyard, while D602-D604 were sold to Cashmore's of Newport who broke them up far sooner due to the former concentrating on easily processable wagons before locomotives. As the fleet only lasted eight years in revenue-earning service, D601 actually spent more time in the scrapyard than it did hauling trains on the main line.

No Class 41s were preserved, nor were any mainline North British diesel or electric products save for Class 84 25 kV AC electric locomotive No. 84001