@Pacific231G
Thanks for a very interesting comment. I'm not sure how far Crompton was inspired by Norris's locos, but he can't have been unaware of them. There is one noticeable difference between the two engineers' locos: on Crampton's designs the driving wheels tended to be large for speed, while Norris's drivers tended to be small for power. The Birmingham and Gloucester Railway used its Norris 4-2-0s to haul freight trains up the Lickey incline, but used more traditional British 2-2-2s with large driving wheels for its express mails.
BTW the forerunner of the Norris design is Edward Bury's small bar-frame locos, as used on the London & Birmingham, London & Southampton, Liverpool & Manchester, etc. William Norris nicked Bury's design, beefed it up a bit and replaced the front axle with a bogie to cope with the roughly-laid track of the early American railroads. Bury tried to sue him in the US courts (Norris was based in Philadelphia) but lost. I often think that an H0 Norris could be made into an 00 Bury pretty easily.
Yes, in the late 1830s and early 1840s British, European and American railways are using very similar designs, mostly British as you say. And the British companies all tended to buy standard locos and stock from a few commercial builders, so that most early models can be used in a range of settings. For example my own little layout could represent a small branch in New England or southern Austria just as much as one in Gloucestershire. It would just need a change of backscene to move the layout to a completely different country.