@the1gofer,
It looks like a scene from the English Civil War, the soldiers look like Parliamentarian soldiers or “Roundheads.” as they were commonly called.
There is no castle Basil, but there is a town in Essex called Basildon and there are castles nearby.
After the restoration of the monarchy under Charles II the Royalist movement was romanticised and still is to a certain extent, Royal Oak being a popular pub name.
This embroidery looks like something made to depict the ‘awful behaviour’ of the Roundheads at a later date.
Sorry I can’t be of any more help.