Did you let it run for a wee while? If you just "cracked" it off and immediately retightened it you may not be seeing the air.Release the bleed screw this morning and didn't seem to release air as fluid came straight out.
Sounds like a Sunday job!
Thank you for the advice, will report back.
From your description regarding the heater hoses it sounds like the matrix might be partially blocked. With engine running and up to temp if you leave the heater fan off - so no air is being forced through the heater matrix - both inlet and outlet pipes to the matrix should be pretty much the same temp (ie. hot) If it's cold weather and you're forcing air through then the outlet hose will be cooler than the inlet but not "cool". Reverse flushing with a garden hose, if you have good mains pressure, is what I'd do.
This thread has made me think about a couple of aspects which have puzzled me. People talk about the rubber seal degrading and allowing coolant to bypass the thermostat when it's cold. I've done a few thermostats over the years on these engines and I've not yet come across this rubber seal? The thermostats come complete with the housing and, try as I might, I can't see any rubber seal. I even dismantled the one that I removed from Becky but saw no rubber seal.
I've come across 3 types so far. This is the one that fits the older engines: https://www.shop4parts.co.uk/?name=store&op=Product&ProdID=470 It's the one that fits my 2010 60hp Eco Dynamic. The later 69Hp engine uses this one: https://www.shop4parts.co.uk/?name=store&op=Product&ProdID=18857 and you need to be a bit careful when ordering it because the 169 model Panda started using the 69Hp engine in 2011 so uses this thermostat but up 'till then it used the 60Hp engine so needs the earlier - cheaper and simpler - version. My boy's 2012 Punto with the 1.4 8valve - so still a FIRE engine - has this one: https://www.shop4parts.co.uk/?name=store&op=Product&ProdID=8263 which you'll notice has a second take off hose connection. My advice is to look very carefully at what's on your's and order one to match. If you go by model year you may end up with problems as you can see with S4p's recommendation for all 09 to 12 1.2 Pandas. By the way this is the only error I've so far come across on the S4p site - a supplier I like and trust. Another thing worth knowing is that the genuine Fiat item does not come with a gasket - hence S4p showing it separately - however if you buy an aftermarket version, I went with the Original Birth from them (and it's been absolutely fine) there's a gasket included in the box.
Worth knowing also, while we're talking about Original Birth (and other unfamiliar brands S4p sell) They source these direct from Italy and I've had a variety of different brands, including some front struts I'd never heard of, and everything has been fine.
The other thing is this thing about the temp gauge reading dropping on long downhill runs. I'd not noticed this on Becky so the last time I took her out to my boy's house south of the city I decide to look out for this. Going out of the city on the bypass I turn off onto the new (relatively new) Dalkieth bypass A68. This main road does a long, maybe 2 miles - might be a little more, climb up out of the Forth Valley towards Pathhead It's just climbable in 5th with foot flat to the floor the whole way but I don't do that preferring to slow slightly, select 4th and go up it on about three quarters throttle at which she goes very nicely at about 55MPH. The temp gauge holds steady at the half way mark, as it does for normal running. On the return journey, if I select 5th, she descends the whole way at approx 60mph (which is the national limit on this road) on a mostly closed throttle all the way and I see no drop on the temperature gauge needle. It's very open and quite windswept so I'd have thought I'd see this effect happening here? Not that I'm concerned about it, I'm very glad to see the temp being maintained.