looking for an old English or British black-and-white series of boys’ adventure movies – there was a series of three movies – they featured 3 brothers (obviously not real brothers) who go on mystery adventures – in the first one, the boys come up from a beach, find an old man who gives them binoculars and a secret map – they end up in a mad scientist’s laboratory – the three boys are called the (something) brothers? or maybe the (something) boys? Date: 1940’s or early 1950’s?
Hey! This is a total shot in the dark but it sounds like a plot from The Hardy Boys, which was adapted by Disney into a series in black and white!
Here is the wiki link and maybe you can check it out to see if that’s it!
https://en.m.wikipedia.org/wiki/Hardy_Boys_(Mickey_Mouse_Club_serial)