It wasn’t just the British system it was just the culture at the time for everywhere.

France, Belgium, the Netherlands, Switzerland, Sweden, Norway...

I don't mean to say that Britain was some barbaric backwater with this. You are certainly right that this treatment was common in other states, even if not universal. But it was very much a case of Britain doing something that was no longer regarded as essential to the behavior of a civilized state to one of their most brilliant minds, a man who was a hero who saved thousands of British lives at minimum by his efforts. It's a reminder of how brutish we can be by adhering to established norms without consideration of their reasoning.

The United States was far further behind the times at that point in time Britain.

Speaking as an American, I might suggest that using the social norms of the US of the first half of the 20th century as a yardstick might be setting the bar a bit low.