4-8-2
United Kingdom
### United Kingdom

The United Kingdom's entire population of Mountain locomotives consists of *Hercules* and *Samson*, the two  gauge  locomotives of the  [Romney, Hythe \& Dymchurch Railway](/wiki/Romney%2C_Hythe_%26_Dymchurch_Railway "Romney, Hythe & Dymchurch Railway") in [Kent](/wiki/Kent "Kent"), England. The locomotives were built by [Davey Paxman](/wiki/Paxman_%28engines%29%23Davey_Paxman "Paxman (engines)#Davey Paxman") in 1927\.

The [Southern Railway](/wiki/Southern_Railway_%28UK%29 "Southern Railway (UK)") considered using 4\-8\-2s for express trains before changing to the 2\-8\-2 and eventually 4\-6\-2 design, leading to the [Bulleid pacifics](/wiki/SR_Merchant_Navy_class "SR Merchant Navy class"). The [London and North Eastern Railway](/wiki/London_and_North_Eastern_Railway "London and North Eastern Railway") had designs for 4\-8\-2s, but during WWII the British government forbid the development of express passenger locomotives, so the plans were dropped. Following the LNER chief mechanical engineer [Sir Nigel Gresley](/wiki/Sir_Nigel_Gresley "Sir Nigel Gresley")’s death from illness in 1941, neither [Edward Thompson](/wiki/Edward_Thompson_%28engineer%29 "Edward Thompson (engineer)") nor [Arthur Peppercorn](/wiki/Arthur_Peppercorn "Arthur Peppercorn") resumed the 4\-8\-2 project, and after the United Kingdom nationalized private railway companies into [British Railways](/wiki/British_Railways "British Railways") in 1948, only 4\-6\-2s were pursued as express locomotives with the [BR Standard Class 6](/wiki/BR_Standard_Class_6 "BR Standard Class 6") and [7](/wiki/BR_Standard_Class_7 "BR Standard Class 7") (though they were classified as mixed\-traffic), as well as rebuilt versions of the aforementioned 4\-6\-2s of Bulleid’s design, which would last until [dieselization](/wiki/Dieselization "Dieselization").


Did the UK's focus on dieselization lead to a decrease in steam locomotive development?