After a few months in service with the “Rocket”, Stephenson used the experiences to develop an improved successor. Since the placement of the cylinders of the predecessor was unfavorable for the running characteristics, the driving axle was moved to the rear and the cylinders were installed horizontally in front of the driving axle and inside the frame. It was probably the first locomotive with this arrangement, which later became the standard.

This arrangement not only improved the running characteristics, but also allowed the cylinders to be mounted inside the smokebox, thereby reducing losses from condensation. Also new was a steam dome, with which dryer steam could be extracted from the boiler. In addition, the front and rear buffers and couplers were roughly in the places where they are today.

On November 23, 1830, it was able to prove its performances by completing the 31 miles from Liverpool to Manchester in about an hour. The prototype was followed by six more by Stephenson and three made by Fenton, Murray and Jackson to the same design.

In the years that followed, many locomotives were built in several countries based on the “Planet” pattern, so that the 2-2-0 wheel arrangement was later named after it. The Liverpool & Manchester alone got 16 of them. The original “Planet” was first modernized in 1833 and retired in 1840. A replica that was built in 1992 was used regularly until 2017.

One of the most significant locomotives of all times was the „Rocket”, built in 1829 by George and Robert Stephenson for the Rainhill Trials which were held by the Liverpool & Manchester Railway. In these trials, the L&MR wanted to determine the design for a locomotive that could successfully operate light passenger trains over longer distances. The new locomotive had to achieve an average speed of 10 mph (16 km/h) over the 70 miles from Liverpool to Manchester and back. The limit for four-wheeled locomotives was set to four and a half tons, while six-wheeled locomotives were limited to six tons.

Since the Stephensons recognized that a single driving axle would be enough for the light trains, they chose the 0-2-2 wheel arrangement for the first time. In this case the driving axle was at the front and the cylinders were mounted behind it at an angle of 38 degrees. The rear wheels were not connected to the driving wheels and only carried the weight of the firebox. 

The boiler had many features which could be found on later steam locomotives. Instead of a single or two flues, it had 25 tubes which created more surface for the smoke to heat the water. These worked great in conjunction with the blast pipe to provide enough draught. Additionally, the firebox had a water jacket to utilize the direct radiant heat from the hottest part of the boiler.

“Rocket” easily won against its rivals in October 1829 and so the Stephensons could share the £500 prize with Henry Booth from the L&MR, who had provided valuable input for the design. It took part in the opening of the railway on September 15, 1830 when the Stephensons had already built the even more advanced “Northumbrian”. The event was overshadowed from an accident in which “Rocket” struck and killed William Huskisson, the MP for Liverpool.

In 1831, when some similar locomotives had already been built, the cylinders of “Rocket” were mounted in a more horizontal way to match “Northumbrian”. It was used on the L&MR until 1834 and then it was unsuccessfully used by Thomas Cochrane to test steam turbines. Rebuilt back to conventional cylinders, it was sold to the Brampton Railway in 1836 and used there until 1840.

After a period of storage, it was donated to the Patent Office Museum (Science Museum) at London in 1862, where it rested until 2018. After some time in the NRM at York, it came to Shildon in 2023. Over the years, several working and stationary replicas have been built. The most popular replica was built for the 150th anniversary in 1979. The original locomotive can today be seen with its nearly horizontal cylinders, while this replica still has them inclined by 38 degrees.

Francis Webb developed the 17 inch coal engine in the early 1870s as his first design for the LNWR. It was created under the requirement that production and operation should be as cheap as possible. These three-axle machines were sometimes described as the simplest and cheapest in the country, but on the other hand they were generally extremely successful with typical British maintenance. A total of 499 were built in 19 years.

One locomotive demonstrated that it could be built, including building up steam, in 25.5 hours. They could pull coal trains of 541 tons at a speed of 25 mph. From 1905 onwards, 45 were rebuilt into saddle tank locomotives. During the First World War, many were used by the military abroad, some even in Palestine. The LMS took over almost half in 1923, the British Railways received 35 in 1948 and used the last until 1953.

In 1880, Francis Webb introduced a new class of goods locomotives for the LNWR. Based on his 1873 “17 inch coal engine”, it had larger cylinders, a slightly larger boiler with a higher pressure and larger driving wheels. The official name of the new class was “18 inch Goods Engine” due to the cylinder diameter, but it was also called “5 ft 0 in Express Goods” due to the size of wheel centers.

Within 22 years, 310 locomotives have been built. Due to their large LNWR crest on the splashers, they got the nicknames “Cauliflower Class” and “Crested Goods”. With the grouping in 1923, they were put into LMS power class 2F. At this time, only two had been withdrawn. British Railways still inherited 69 in 1948 and withdrew the last ones in 1955. A class that had been derived from this class was the 0-6-2T “18 inch Tank Class”.

By reducing the driving wheel diameter from 75 to 62.5 inches, George Whale, superintendent at the LNWR, developed a locomotive for mixed service from his Experiment class. The resulting class reached a total of 170 and was officially referred to as “19in Express Goods,” a reference to the cylinder diameter and its primary intended use in front of express goods trains.

Because of their origin they were also called the “Experiment Goods Class”. They were classified by the LMS into power class 4F and were withdrawn from service from 1931. British Railways only took over three locomotives, which disappeared by 1950.

Webb developed the Alfred the Great class as an enlarged development of the Jubilee class. Like these, it had a four-cylinder compound engine. A redesign of the valve gear made them the Benbow class. After the Jubilees had been converted into two-cylinder simples, the same thing happened to 25 of the 40 Benbows from 1913 onwards. These, like the rebuilt Jubilees, came to the Renown class. 39 locomotives came to the LMS, the rest were retired by 1923.

Instead of ordering another batch of the class 1185 with a 0-8-2T wheel arrangement, H.P.M. Beames developed the class 380 with a two-axle trailing bogie to get more space for the supplies. Their area of application was the steep and winding lines in the valleys of South Wales, on which they were to pull freight trains and, if necessary, also be used in front of passenger trains. When the locomotives were delivered, the LNWR had already been merged into the LMS, where they were classified in power class 5F. 14 of the 30 locos survived the founding of British Railways, but these were retired by 1951.

Between 1893 and 1900, Francis Webb built 111 class A 0-8-0 goods locomotives for the LNWR. Like earlier Webb compounds with two driving axles they had two small high-pressure cylinders on the outside and one larger low-pressure cylinder on the inside. But unlike these, all four axles of the class A were coupled.

Since Webb's successors Whale and Bowen Cooke wanted to clear the problems of the Webb compounds, they rebuilt the whole class into two-cylinder simple locomotives. So 15 became class C, 62 became class D and 34 became class C1. Most were again rebuilt to class G1 and some of these again to class G2a, with the last ones only being withdrawn in 1962.

Based on his class A three-cylinder compound, Francis Webb designed the four-cylinder compound class B for the LNWR. Between 1901 and 1904, a total of 170 were built. They earned the nickname “Swami” after magicians who used to disappear in a cloud of smoke. Like their predecessors, they had clearly visible inclined outside cylinders, but here these were smaller. Due to the four cylinders, they were fairly top-heavy with 31 tons on the front two axles and only 22 tons 10 cwt on the rear two axles.

So the numerous rebuilds of class B started when George Whale rebuilt 26 with a leading axle and designated them class E. Ten class F locomotives rebuilt between 1906 and 1908 also had a leading axle, but also a bigger boiler. 32 two-cylinder simples rebuilt between 1912 and 1927 were designated class G. Here the two bigger inside low-pressure cylinders were used as new high-pressure cylinders.

Another more comprehensive rebuild took place between 1917 and 1927 when Bowen Cooke rebuilt 91 class B locomotives to the superheated two-cylinder class G1. Additional locomotives of classes E, F and G and even the rebuilds of the class A were also rebuilt to class G1. Some even lost their leading axle again when the outside cylinders were removed. So the LMS had only taken over 53 unrebuilt locomotives of class B in 1923, but rebuilt more of them. In 1927, only ten unrebuilt locomotives were left over which were withdrawn within a year.

Since the locomotives later designated as LNWR class B had poor running characteristics due to their four cylinders overhanging at the front, George Whale added a leading axle in a Bissel bogie. Although there were no other changes, they were placed in a new class. A total of 26 class E locomotives were built between 1904 and 1908, when the last class B locomotives had just been delivered. Only six were retired as class E by 1927. Two were given a larger boiler and thus became class F. The rest were rebuilt into class G1 between 1917 and 1924, which again had the 0-8-0 wheel arrangement and only two cylinders without compound action.