Right so something very similar happened to me about three years ago in my old place in Basingstoke. Whatever was up there, my dog absolutely refused to look away from the ceiling for a good two hours after the sounds stopped. Animals pick up on something we just can't, thats my belief anyway.
Did the footsteps have a particular rhythm to them or was it more random? I've read accounts where the pattern actually matters in terms of what you might be dealing with. Also did you feel anything - temperature drop, pressure in your ears, anything like that?
The reason I ask is I've been looking into cases where roof disturbances and animal behaviour line up like this and theres a pattern that keeps coming up. Would love to know more details before jumping to conclusions but honestly this sounds like it could be worth documenting properly if it happens again.