[madcjd]

Doing my usual, twice monthly, drive between Lancashire and Heathrow.....
Driving home on Sunday evening, I hit a terrible jam on the M6 (no shocks there), which added about an hour to my journey.
Not long after that sitting around I happened to notice my coolant temp gauge had just gone slightly to the left of 90 deg - it always sits dead centre once up and running, so this was a first.
I continued to watch the temp fall to 70 and then work it's way to midway between 50 and 70 deg.
I pulled into the Knutsford services and give her 5 minutes to sit with ignition off and then inspected the engine bay.
I shone a torch into the header tank and the coolant was still pink and uncontaminated (I think I was half expecting an oil cooler fault chucking oil into the coolant!)
Nothing else obvious to see either.
So, I set off again (carefully) for the last 70 miles and initially the temp climbed a bit, but then resumed to the 50-70 range.
My initial thoughts were thermostat stuck open or temp indication (sender).
The next day, yesterday, did some local driving and the coolant got up to temp and sat nicely at 90.
I think the next motorway run will tell the truth. I have priced up a new thermostat, but, then it was mientioned it could be the pump at fault?
Any thoughts out there?