Thank you, Ray. That's very interesting - I did search the message board for "River Cannich", and got only one entry from January 2012, referring to terrain north of it. (Also useful, in fact).

I've now read all the thread you refer to, and have also checked Geograph. I see there was one map mentioned which suggested a ford over the river - but the famous JD cautions that the water level is very variable.

Seems it might be worth a quick look but I'll need a Plan B.

[John J - where are you coming from to there? Sadly can't walk on with you, I'm heading south.]