First floor flat own entrance, fire door?

[First floor door]

Hi,

Apologies if this isn't posted in the correct place. I am currently selling my flat. It is a one bedroom ground floor in an old converted building with it's own entrance. My buyers solicitor is telling my solicitor I need to agree to install "an FD30S and provided with intumescent strips, cold smoke seals and a self-closing device, mounted on three fire rated BS 1935 hinges". 

My query is that my flat door does not connect to any common areas. It goes directly to the outside on the ground floor. There are no other flat entrance doors near mine. Is it a legal requirement to have my door changed before I can sell the property or not? I don't really want to spend a load of money I don't have to unless it's absolutely legally required. If it is then fair enough but none of the other flat doors with their own entrance have this. Just the common areas have proper fire doors from the hallways for the flats within the main block.

 

[AnthonyB]

No it isn't - an external entrance door does not need to be a fire door unless onto an external escape stair or a balcony with escape in only one direction.