Well meaning friend

Why not just look on the stray man as a potential friend? The more the merrier if you are a bit lonely surely?

Well, if she asks again could you say 'oh no, that's far too much trouble for you, let's have lunch out instead'. If she contrives to bring someone, well so could you, and it's less embarrassing in a crowded place. I wonder if the gentleman had been pre-warned about her matchmaking? Presumably he thought dinner was a twosome with your friend.

Social gatherings with a friend/s are the way to go then you can either stick with it or slide away if it doesn't suit. That way nobody feels under an obligation and no excuses are necessary. Nobody likes being put on the spot in any situation.

My elder brother,82,is the "spare"man in similar circumstances,but does enjoy being with different people,nothing romantically biased,but just "friends",he usually jokes and laughs with the ladies,and they seem to enjoy his company,gives him a twinkle in the eye,so just take it as face value,and enjoy the company,but you can make it quite clear you are not looking for a relationship,and ask friend to invite one or two others to make a little group,or as others have suggested, invite them to yours ,I'm sure the spare man would also be relieved not to have the situation so pressurised

At least some gives a damn about you.

You're not looking for a man. That's all there is to it.
Go along to her invitations confident that you know your own mind and enjoy yourself.

It won't matter the number of men she invites because they are of no interest to you and you'll make that clear to her and the man while you are at the dinner/occasion. Politely but firmly.

Be nice to the man but make the impression that you are bemused should anyone think you're in need of "courting".

Have a laugh and explain to the potential boyfriend how you've both been set up by your friend. Tell him you're not looking for a partner, but a new friend who shares common interests is always welcome. Don't be embarrassed, enjoy yourself.

Hahaha. I wish one of my friends would do this for me.

I'm with you 123kitty. I'm not sure why this man is 'a stray old man'? Men can be just a good friend as a woman.