Slap sound from drivers door / B pillar

[darrude]

Hi just wondering if any body else gets the same slapping noise. I can only think to describe it as a "slap" sound like the entire door is moving. 

Only happens whenever going over medium bumps, send particular worse when the left front wheel good down a pot hole.  Really, really starting to annoy me...

 

Any help would be most appreciated, I've tried holding every panel, the belt adjuster, grab handle, seat, windows in the front and back (with the help of my eldest) of the car and still can't isolate it.

Many thanks

 

Darren

 

[Chris.S]

only thing i notice on mine is when the passenger seat belt buckle it halfway down when not in use it taps between the seat and b pillar, if i push the buckle to the top it stops it