Re: So, to sum up. . .
"As an isolated nation the UK will have far less clout in the world than it did as part of a larger block"
Not necessarily true.
An "isolated UK" would be expected to have less clout than the very much larger block as a whole.
That block consists of 28 nations; if the majority opinion is one that benefits the UK, the UK has more clout. However, there will be times when the EU opinion is contrary to the UK's interests, and then the UK has no clout at all.
It also ignores the fact that an "isolated UK" acting only in it's own interests should be much more nimble in making a decision than the much larger block of 28 different opinions that have to be welded into one. Sometimes, clout can come from being swift to make a decision (or at least being the first to make a decision).
So at times the UK will have less clout. And at times, it will have more.
And of course outside the EU, the UK isn't an isolated nation. The UK is part of numerous bi-lateral, multi-lateral and international treaties and agreements, and your use of the word 'isolated' is inaccurate and misleading. I suspect deliberately so.