Loads of good suggestions, thanks.
Kim, I think the Thermolites might be warmer than I need. I don’t have a shower at the work end of my commute so I try to avoid getting overly warm en route (e-bike helps on that front). Some of the other suggestions look a bit toasty too.
I’m thinking of the Lusso Cooltechs for that reason - thanks Giropaul, I’d forgotten about Lusso. If you were borderline, would you size up or down?