I am not so sure that the UK was well-placed to supply the world. Because we were first our railways developed from horse-drawn waggon ways and carriages and that was a big factor in determing our loading guage which still limits what we can do on existing railways.
The Empire meant that initially British equipment and practice found its place around the world but don't forget that the Empire didn't give up its riches for free, someone had to pay for the railway, in the beginning that would be the UK. As the Empire became the Commonwealth the now independent countries either look to built locally or to seek equipment better matched to their needs. US practice must surely suit much of Canada, Australia or India better, especially outside of the large population centres.
Also we didn't exactly help ourselves, British Railways inherited the different ways of 'the big four' and didn't standardise enough, (perhaps because of lack of money, perhaps to avoid upsetting the workforce?). Post World War 2 the nations of continental Europe had the desire to move towards inter-working. That led to common standards, which in turn produces a bigger market ultimately dominated by fewer but bigger suppliers. Until the Chunnel inter-working between countries was never a concern for the UK, except for limited waggon traffic. (With the rise of containerisation was that considered important? BR didn't have to 'lose' a vehicle on a run from Manchester to Milan if the customer's container could easily be transhipped).
Don't forget that big organisation aren't as single-minded as many outsiders seem to think. BR's APT was a product of new thinking, the smart youngsters ftom the universities and people with solid aerospace experience set inside a world literally with a cast-iron culture. (My father, with an aircraft and car manufacturing background, observed that no airline pilot would put his feet up on the dashboard or tip the contents of his 'billy can' out over his aircraft's nose, and that explains why a diesel loco 'needs' and armour plate glass cover to its dashoard and a 747 doesn't). Meanwhile there were the existing staff of the CM&EE department developing the HST. Which was the right approach? The APT appeared to fail but the principle was imported with the Pendolino. HST is still with us, (just), and the design even made it to Australia!
There are no easy answers I am afraid. Looking to politics is unlikely to be the answer though, nobody is in the job long enough. A sucessful engineering sector really needs a culture for success and our politicians and broadcast media all too often work against that.