Como dizer "Pessoa de poucos amigos (não sociável)" em inglês

Bad mixer, not a good mixer, not a people person, not a mingler, not a sociable/social person

I cycled from Cardiff to London that day – it would be in 1951 I would say. R. Palme Dutt was there but did not stay long. He is a bad “mixer”. Ref. breakingthefetters

(...) whom Thompson describes as a “performer not a mingler … a rock star … working on the theory that one really big crowd is better than forty small ones.” Ref. tabletmag

A: - What did I do to him?
B: - Shake it off!
A: - No, there's something wrong.
B: - Nothing's wrong. He is not, so to speak, a people person.

Cf. O que quer dizer "people person"?
Cf. Significado de "A social butterfly"
Cf. Como dizer "Nada amigável/Cara de poucos amigos" em inglês