It is often perceived that mainline locomotives were the back bone of the United Kingdom. This however isn't necessarily correct. On a vast number of industrial sites around the country, both large and small, industrial locomotives would work day and night unassumingly moving wagons to supply all manner of goods for both home and abroad. These locomotives often didn't get the attention from enthusiasts that their mainline counterparts did and therefore fell under the radar.
It is often a surprise to people when industrial petrol and diesel locomotives were introduced. The large scale use of petrol locomotives can be traced back to the first word war when railways were used to carry supplies to the trenches, however these were only small locomotives of 20-50hp. Large diesel locomotives were developed in the 1930s and by the 1950s modern reliable diesel locomotives were being used in many locations. Unfortunately the large scale manufacture of diesel locomotives ended in the 1960s when many well-known locomotive builders went out of business.
For all that the post second world war era was a golden age for industrial locomotives, the writing was already on the wall thanks to the increase in lorries and construction vehicles. Many internal movement in factories and quarries changed from being railway based to lorry. While some industries, such as steelworks, have found that railways are still the best way of moving heavy and dangerous loads. It is now rare for smaller factories to use railways at all. They have been replaced by forklift trucks and containers.
It is fortunate that a good number of industrial diesels have entered preservation as they are not held in the same regard as steam or mainline locomotives and to be fair in many cases they are not capable of hauling passenger trains on a regular basis. Unfortunately they are usually the first to be dismantled or sold when repairs are needed. A regrettable number have been scrapped in the 21st century while many others are unused and unloved thanks to mainline diesels becoming available like the overrated popularity of the ex British Rail Class 08.
Nowadays in industry there is an increasing trend towards heavily rebuilt or even new build locomotives that incorporate computer control, environmentally clean engines and hybrid drives. Even some small industrial specialists are rebuilding locomotives with these modern systems that when designed and implemented properly will offer higher reliability and lower costs. So in conclusion this is why these historically important locomotives should be more at the forefront of todays preserved railways. They most certainly have a place in preservation.