Many thanks Paul, that worked like a dream.

Just one slight problem is where a sentence finishes with a single- or double-quote mark:

... and "this is the end of the sentence123."

becomes:

... and "this is the end of the sentence.123"

So I think the code needs to take into account other punctuation marks to make it more universal:

Quote '
Speech "

I doubt that other marks would feature.

Once again, I really appreciate the time you've taken