Thanks so much for the reply.
However - the '<' & '>' characters aren't in the original document - I've used them to denote a substitution of a URL as the BB code here doesn't let me include the literal text, which the BB would try and interpret as a hyperlink and prevent me from posting altogether as my post count <5 ! I've used asterisks below to denote the substitution this time:
Testing text
Original URL: *some URL* some other text

testing

I can autodetect the beginning of the URL, but I can't programmatically select just the URL without automatically selecting any surrounding text.

I'm finding this frustrating because I'm a reasonably experienced programmer, and Word seems to have a will of its own, doing things I've not told it too!