It was one of my favourites in childhood, given to me by my grandmother but sadly it's been lost and I'd love to find another copy.
It features a girl called Trudy who moves to a small village with her parents. She has a dog called Rebel and a cat called Tibby. The villagers are all afraid of 'Workhouse field' and won't go near it due to a tragedy that occurred at the workhouse years before.
Trudy ends up going back and forth in time to the workhouse and helps the inmates. Back in time she is another girl from a wealthy family who has TB I think, Elizabeth May??
The workhouse master has three little boys. His name is Matthias I think.
In the end the inmates set a fire at the workhouse and manage to escape.
Does this sound familiar to anyone?