Well, I said I'd report back.
So, my Eurostar experience. The latest trains seem to be better than the originals, and this is the first time I've gone via St Pancras. My last times were from Waterloo, with the consequent 'leisurely' ride through southern England. At least this time, we were up to speed pretty rapidly, and I was amazed how short a time it took to cross the Medway.
Going out, we had one change at Brussels, and the Thalys to Amsterdam was decidedly down at heel - looks like a rebadged TGV hand-me-down.
Coming back, there were no changes, but to be honest, four hours sitting in a train seat is not much fun, especially as one loud woman was holding several Zoom meetings on her laptop the whole time. Of course, the British way is to ignore and tut loudly, but the Dutch are much more direct. Didn't seem to have much effect either way.
The check-in terminal at Amsterdam reminded me strongly of a temporary tent I once used at Coventry airport when low-cost air travel was in its infancy, before mobile internet. Nothing to do, lots of sitting about pondering death, and listening to other people's travel anecdotes ('last time I was in New York, the security was so shit, blah blah blah'......'when I flew through Dubai, I couldn't believe the heat in the terminal, blah blah blah') - why do we do that?
The whole experience invited comparison with the flying alternative, and to be honest, I wish we'd flown. The price would have been the same with BA Business, and at least we'd have had airport lounges, and a much shorter travel time. Like, two hours shorter, as the check-in times on train and plane are very similar for some reason. No Zoom calls either, which has to be a plus.
Shame really, as I honestly thought I could avoid the airport experience. Maybe I just dislike other people. Maybe I should investigate NetJets.
As far as Vermeer is concerned, absolutely fantastic. Absolute genius at work, and I learned a lot, albeit by having the Wikipedia page for each work open as I went round (recommended as there's no multimedia guide). I didn't realise that the presence of lutes and slippers indicated loose morals and fannies.
We also squeezed in the Van Gogh museum in the morning. My brain is now full.