This tv show was a British one. It was set during ww2. There were a group of evacuees staying with different people in the village. Some stayed with a kind old lady and others stayed with a posh couple. The children thought that the couple were either spying or selling on the black market (not sure which) . They spied on the couple and discovered secrets.
It was an educational show, I watched it when i was younger, but can’t remember the name. It could have something to do with ‘i spy’ or similar. Any ideas?
Carries War /
Trying various key words I can come up with a show called Goodnight, Mister Tom that might possibly be it. There is another show called Land Girls that seems less likely to be what you’re looking for. If these aren’t right then sorry I couldn’t help.