The Mack Super Pumper was a locomotive engined fire fighter (2018)

For the curious: most locomotive desiel engine designs have marine origins. That's because ships transitioned to desiel power (from steam) before trains did. At least in the UK. The general design constraints are similar and so when folks began looking into making diesel locomotives they generally selected existing marine designs and adapted them. Often de-rating the maximum power to improve reliability.

When the UK converted from steam to diesel it was easier to switch the locomotives while leaving the coach stock as-is. Modern trains aren't like this: they're "multiple units" with more than one drive car. Anyway, a steam engine can generate much more power than a 1950s diesel engine can, particularly factoring in the UK loading gauge which restricts engine height. So in order to make a diesel locomotive capable of taking over from A4 Pacific steam engines on the east coast main line, it was necessary to design a locomotive that had two desiel engines, with a high power to weight ratio. Hence the class 55 cited in the article. The deltic engines were very complex and costly to maintain but solved a problem arising from the transition away from steam. In the 1970s they were in turn replaced by trains with a DMU configuration (HST), featuring a permanently coupled power/van car at each end, removing the need for a single very high power locomotive.