Good morning and thanks for all the ideas. There's a lot to answer so I'll take it in chunks...
I'll try and look up the Zaffiro pro later, cyberknight, I am trying to avoid the g-corporation and all its works.
Thanks JonBuoy, I rather guessed from the reviews I've started to read that smooth road tyres have become the standard. Maybe it is an aesthetic thing, maybe because I have been known to skid and haul-turn out of trouble, maybe because there will be some towpath riding, I feel I will need some tread. Then again there's these -
https://www.merlincycles.com/continental-grand-prix-4-season-folding-road-tyre-700c-45210.html - so I am not alone in this. Out of stock, naturally,
I have a different bike for hacking, MichaelW2 so I am hoping to rediscover the joys of my fast road bike, and know what I want, and, funnily enough, why. My weight will be evenly balanced, I will be using drop bars and if I hit up some pothole or lump I want to roll over it nicely and keep my speed. I also simply like riding with hard tyres. The Marathons are too chunky, but I'll take a look at the Durano, thanks.
Those road tests -
https://www.bicyclerollingresistance.com/specials/grand-prix-5000-comparison - were very useful indeed. Once I got the hang of the site I was intrigued, so big thanks cycleops.
Please forgive me for not clicking 'like' buttons - I have some qualms with social media cultural shortcuts, but that doesn't mean your ideas are not appreciated!