These engines, or a version of them would also find themselves fitted to a test bed for a new class of British diesel engine in 1955, christened as DP1 but nicknamed 'DELTIC' after the engine. This nickname may have been enforced on the public by the designers of the locomotive, who has 'DELTIC' painted on the side of the model in the same cream as the lining nameplate style.

DP1 was built by Dick, Kerr and Co. in Preston, and would be outshopped in 1955 in a unique colour scheme of baby blue and cream. The was not initially a stylistic decision, with the cream lines on the side being more than paint, with the paint applied over aluminium strengthening beams on each side with the intention to break up what would otherwise be a very tall, straight slab sided locomotive.

DP1 would be in service with BR in its original colour scheme and condition until November 1960, when an enormous oil leak was discovered on one of the engines, something that could lead to terminal engine failure if not addressed. The locomotive was sent back to English Electrics works however work on the locomotive was not given the go ahead with the model being officially withdrawn from BRs locomotive roster in 1961. 

The locomotive would be stored for a few years before being donated to the science museum in 1963. The locomotive has never run in preservation, largely due to the fact that it has either been inside on static display in various museums and due to the fact that engine components were removed after the failure with the engines fitted to the resulting Class 55 'Deltics' being sufficiently different enough to prevent the pool of BR spares to be used.

In 2023, the Hornby Dublo Deltic model fills a hole in Hornby history, with the DP1 Deltic featuring on the cover of the 2nd edition catalogue in 1960, but never actually being made in physical form unlike the Class 55 Deltic, which did receive a Hornby Dublo incarnation. This model is fitted with a diecast body, 21 pin DCC decoder socket for digital operation, a 5 pole motor with dual flywheels and dual bogie drive. This is surely, not a Dublo model to be missed.