Puzzled - Possible Pied Flycatcher Sighting

When out on Saturday I noticed a bird with black and white colouring and a very distinctive flight.  I haven't seen anything like this before but I was wondering if it was a Pied Flycatcher.  The colouring seemed to match but I can't find any description of the flight of a Pied Flycatcher anywhere in the books I have.  The flight was like a very exaggerated bobbing almost like an old fashioned roller coaster when I saw it but it may just have been after flies on the wing.  Apologies that this is vague but I didn't have anything to take a picture with or record the flight.

Thanks

Philip