Ah lots of useful info in these replies
@engkin, this:
((\d+/)?\d+)
Worked perfectly, thanks very much
@eny, Am already using RegExpr, it looks like it didn't need the forward slash to be escaped, I'd probably have known that if I'd RTFM so thanks for pointing me toward it,
([\d/]{1,})
work great, but in instances where there is a C/O in the address it picked out the slash.
I'm trying not to use external units in my program as this is as much an exercise in learning pascal as anything else. It's much easier than C++ which is a major point in it's favour AFAIC, I'm just trying not to dive too deep into the rabbit hole until I've got the basics down