Hi, 

please help this newbie.

I am getting mixed messages from my architect and my builder about where I need fire doors.

The current flat is on a the ground floor of a four storey listed building.  There is a communal area and we have our own front door.  The front door seems to be a fire door but the rest of them are the original Victorian doors.  
We have a cellar, current accessed by an outside steep staircase.

We are about to knock through the floor and put an internal staircase in. We are planning to have bedrooms in the cellar and a sitting room and kitchen on the ground floor.

So, given that the flat will be two stloreys  do I need to put fire doors on all living rooms off the stairwell?

thank you in advance. 

I cannot give you a definitive answer but in my opinion you require to provide a 60 minute separation between the ground floor and the basement which could be achieved by a FD60s at the ground floors or enclose the stair case and provide a FD30s at the ground also basement level, you will most probably need to keep the external staircase for MoE. You need building regulation approval so you need to contact your local Building Control get get their approval.