The class 79 of the London, Tilbury & Southend Railway was a 4-4-2T tank locomotive for fast suburban trains. It was designed by Thomas Whitelegg on the basis of his class 37, that has in turn been designed based on William Adams' class 1. What all had in common was that they had outside cylinders and inside valve gear and a saturated boiler. With their 6 ft 6 in drivers, they could reach 65 mph (105 km/h).

The LT&SR only ordered four from Robert Stephenson & Co. which were delivered in 1909. When the Midland Railway took over the LT&SR in 1912, they were assigned to power class 3P. The next order of ten was placed by the MR, but only delivered directly to the LMS after the grouping in 1923. 25 more were ordered by the LMS in three additional batches and delivered between 1925 and 1930.

No. 80 “Southend-on-Sea”, later “Thundersley”, on a colorized post card

What was special was that even the last batch of this class was built in 1930 with a saturated boiler. Later they were removed from the earlier LT&SR network and used in the East Midlands. British Railways had taken over all 39 locomotives and withdrew them between 1951 and 1960. No. 80 from the first batch is the only one that's existing today. It is on static display at Bressingham and again carries its original livery.