Vague-memory request time:
- When I was a kid (around 1992-1996 era)...
- ...I remember reading a series of books (perhaps a trilogy, possibly more)...
- ...about these kids (3 kids, perhaps? I'm sure they were siblings, too)...
- ...who went to an old house (on holiday... I think...) each year...
- ...when there, they would travel back in time (through a mirror? I might have made that bit up)...
- ...to a point at which this house was occupied by a wizard...
- ...and, in this past dimension they could transform to animals (I'm pretty sure that the oldest sibling transformed himself into a fox)
They had various tasks/missions in order to help the wizard and his friends.
I wish I could remember more than this; the only thing that I can concretely remember is that I really enjoyed them!
Ringing any bells with anyone?