Roller shutters should have a manual device which would allow operation in the event of a power failure:

Regulation 18 of the Workplace (Health, Safety and Welfare) Regulations 1992

1. Doors and gates shall be suitably constructed (including being fitted with any necessary safety devices). 

2. Without prejudice to the generality of paragraph 1, doors and gates shall not comply with that paragraph unless: 

a. Any sliding door or gate has a device to prevent it coming off its track during use 
b. Any upward opening door or gate has a device to prevent it falling back 
c. Any powered door or gate has suitable and effective features to prevent it causing injury by trapping any person 
d. Where necessary for reasons of health or safety, any powered door or gate can be operated manually unless it opens automatically if the power fails 
e. Any door or gate which is capable of opening by being pushed from either side is of such a construction as to provide, when closed, a clear view of the space close to both sides.

I'm guessing someone has either lost or misplaced the pole which is used to open the shutter in the event of a power failure.