If the only door into a particular area is a fire door, and people regularly work in that area should that fire door be closed even when somebody is working in that area. If there is a fire outside that door the person would be trapped inside the area. If there is a fire inside the area again person could be overcome by smoke and people on outside may not realise what has happened inside area.

If the person is in the room sees or smells smoke I would assume he would realise there is a fire and get out long before he/she would be overcome by smoke. Also if there is alternative escape from this room and a fire occurred in other room he/she would escape via the alternative escape. 

However if there is no alternative means of escape then it is an inner room situation and the solution is fully explained on page 70 of the guide to Offices and shops. Three solutions are provided but only two would be suitable for this situation because the door that provides access to the room is a fire door consequently the wall must maintain the required fire resistance.