Adam Richardson, for the MP, told the court in written submissions that the agreement to use the building saw monthly payments of around £1,250 in return for exclusive use of an office at the site and full access for Mr Rosindell and his staff.
After the defection, the association said the agreement for him to use the building was invalid and later changed the locks without notice, with Mr Rosindell’s staff only allowed to retrieve work items under supervision.
Richardson said: “The proper course would have been to seek possession through the court. Instead, the respondent has taken the law into its own hands.
“Such conduct is unlawful irrespective of the ultimate determination of any dispute as to the validity of the arrangements.”
The barrister continued that the lockout was “materially impairing” Mr Rosindell’s ability to serve his constituents and deprived him of safety measures inside the building, including CCTV and a panic room.