a nosy parker
A person who likes to meddle or pry into other people's lives. Primarily heard in UK, Australia. I have to be careful about what I tell Betty because she's such a nosy parker that she'll bombard you with questions at the slightest provocation.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
a ˌnosy ˈparker(British English, informal, becoming old-fashioned) a person who is too interested in other people’s private lives: Our next door neighbour is a real nosy parker. He always has to know everything about everybody on our street.
Farlex Partner Idioms Dictionary © Farlex 2017