Enforcement letter - remove Storage Container, help please! - Public forum - Planning Advisory Service (PAS)

Hi folks I really need your help, I'm facing planning threatening enforcement if I do not remove my 40ft storage container in my residential garden.  Its not fixed and temporary, not facing anyone, movable, non-commercial, wood cladded.  Does not need planning surely! Not on a border (close to the access road but enough away for me to put a border fence up in front of it and not beyond front line of the house either. Help!  Pic attached.  If I posted this in the comments as well I apologise, was not sure how to post initially but think it's meant to be here.

Thanks, Greg