ABANDONED. boating party where no one can manage the boat except one newcomer who everyone thinks someone else invited who takes power over the group

[Bibliosaurus]

I read this many years ago , paperback, library fiction. The plot uses a stranger taking over a group of friends going on a boating holiday ,inland either the broads or a river trip - they all think each other invited him, of course no one did, and he controls them all - I forget with what aim -possibly to dash or destroy the status of the others with their "friends". Any one read it?

[Lobstergirl, au gratin]

Genre fiction or literary fiction?
Author's gender?
Around what year did you read it?
Or when was it published?
Cover?
What country/region is the setting?
Any other plot details you remember?
How big is the boat?

[Daisy]

Bibliosaurus, what do you mean by "library fiction"?

[Sue]

I remember a BBC television play with a similar plot. Was it called something to do with "waters" or "river"?

[Lobstergirl, au gratin]

Bibliosaurus, are you still looking for this or did you find it?

[Kris]

No response, moving to Abandoned folder.

Bibliosaurus (OP) last posted in the group in December 2018.