One of the few remaining regular passenger services to use a proper locomotive is operated by Chiltern Railways. This week-day service runs between Birmingham and London using a modern Class 67 Bo-Bo diesel-electric mainline locomotive.
I have used this service a couple of times recently and have been impressed by the level of service. The British Rail Mk3 carriages used by Chiltern Railways, a design from the mid-1970s, are comfortable, quiet and spacious compared to the vastly inferior modern offerings that passengers now have to endure.
The respective stations between which the service operates, Birmingham Moor Street and London Marylebone, are both delightful century-old Grade II listed buildings in stark contrast to their claustrophobic 1960s equivalents on the West Coast Main Line (WCML).