Found it!

I ended up on a small solway safari.
I was intending to go into town but the traffic on the roundabout at junction 40 was all jammed up so I ended up slipping off on to the M6 north and headed to Annan where I had a wander around the harbour (CheBurns made me smile - extra) and then drove to Newbie to walk the end section of the Annandale Way where the River Annan flows out into the Solway. Once I’d regained my marble I went just a bit further to Powfoot and walked out on the sands as the high tide rushed out like a drain (extra).