I live on the ground floor of a block of 6 flats which are on 2 levels. My flat opens from the front door directly onto the outside. Next to my front door on the outside is a cupboard that I use to store various bits and it also houses my meters for electric and gas.

This cupboard has an old wooden door which was installed when the flats were built in 1998 and now the Housing Association which manage the block (I own my flat) have put a notice on my cupboard door saying 'Fire Door Keep Locked'. My question is: 'is this door really regarded a fire door and am I obliged to keep it locked as over the years I use it for delivery of parcels etc and never keep it locked.

Any guidance would be appreciated.

I doubt it unless someone's external escape route has no option to pass close to the door.