To also add in, one can’t use a comparison with the USA. The USA is a continent-sized power that has all of the resources needed to be completely isolationist.
If tomorrow the USA cut itself off from the rest of the world - including Canada and Mexico, the USA would not only survive but thrive - and that’s not jingoism.
The UK on the other hand is a mid-sized country -bigger than most, but not self-sufficient in food or raw materials. That’s NOT a bad thing - it’s how one plays with the cards one has — Singapore is the same, if not worse, and so it deeply integrates itself with all powers as a trading post. Plus it is also tightly regulated.
The UK boomed in the 1700s because France committed national suicide with the revolution, because the Brits also had a compromise church (the Anglican church took Catholicism and Calvinism and merged it together) and they also were open at a time the French were closed.
The other big stroke of luck was the implosion of the Mughals. Before the death of Aurangzeb in 1707 no European power could go up against the Great Moghuls. After 1707 that power collapsed and the Indian confederation that replaced it, the Marathas, were horribly disunited. Perfect conditions.
The UK took advantage of those once in a millenia conditions and did it well. It deserved its time as a glorious empire.
It can still do well while not being part of a union of countries, but it will need to change
I guess that it doesn’t help that the UK is an island. As you mention, Singapore and I’ll add to the list Japan.
We have also had the advantage of not being in the thick of the WWII. Huge advantages being separated from the action by a bunch of water.
What are its major industries? Bet that there aren’t any natural resources such as fossil fuels. Well there might be coal. There simply isn’t enough land mass.
Either way, I hope that the US see the value of helping a important ally with a common history and language.