I slept 10 hours last night!!!
Went to Honda dealer (also Mitsubishi and Hyundai). Very helpful. Left car for a couple of hours, walked into City, visited cathedral.
Came back, he explained that there is a known problem with CRV and Civic (same engine/gearbox): ratchet mechanism is self-adjusting and can stick so clutch doesn’t fully engage, which would account for symptoms. He couldn’t reproduce problem, so suggested we test with caravan again, it may be solved. Very helpful, no charge.
Phoned Iain and Honda Exeter, and got some support for this, so decided to move on tomorrow. If problem recurs, will return here, if not will continue to near Giverny.
Had lunch at caravan, then bus to les Hortillionages, boat trip on canals amongst cultivated marshland. Beautiful and interesting. Lovely sunny mild weather, ideal!
Walked back to caravan, initially main roads, but then river and canal towpath, nice. Tired, nice cup of tea!