Apparently, this film (also an episode of the American show "Masterpiece Theater") is from a novel very famous in the UK--though I doubt if that many folks in the States have heard of it. "The Railway Children" is a very sweet tale about three siblings who manage to keep up their spirits and do good when their family suddenly is reduced to poverty.
When the film begins, this family lives in a nice home and has no apparent worries. However, soon their father disappears and their mother gives them little idea where the man went. But, she also tells them that now that he is gone, they cannot afford to live in their home and move to the countryside. For some time, they can barely afford to eat--and things get only worse when mother gets ill. So, the three kids manage to do amazingly well to keep the family together, save many lives and live happily ever after.
This is a very nice family film which promotes many nice virtues--such as faith, kindness and a willingness to give even when you are nearly without. Very well produced and extremely well acted by the children. Well worth seeing.
By the way, Jenny Agutter played in the 1970 version of this story (as a child) and here she plays the long-suffering mother.