The building regs applicable would be from the time the work was carried out as these regs have changed over the years so its not possible to give a definitive answer, Reg certs can be applied for any work carried out from 11th November 1986. There have been a number of changes to the regulations to lofts over that period and and not just means of escape, so a date would be required required.There is an open staircase on the landing as the pictures show. The stairs look are quite narrow but when you get upstairs there is a small landing with 3 doors (bathroom, bedroom and office), none looked like fire doors. If them doors were to be replaced with fire doors, what else would be required to get it up to current regulations?
Fire doors on the landing? A closing fire door at the top of loft stair case?
For information self closing fire doors are no longer required in most domestic situations.