Please see below the spec for the soundproofing and fire separation applied to the underside of the first floor across the whole of the GF unit.

Provide and install  2  x  15mm  layers  Gyproc  Soundbloc  boarding  to ceilings fixed directly to joists with suitable drywall screws. Board joints to be  staggered  and  taped.   Install softwood perimeter   and   intermediate   noggings   as   required   to manufacturer’s specification.   Include all downstand beams and   detailing   to   achieve   60mins   fire   resistance.   All joints/penetrations   to   be   treated   with   fire   rated   mastic sealant: See bottom line from the excerpt below from the boarding technical spec.

Along with this there are additional layers of 12mm and 9mm boards applied over the top of the existing floorboards and the floor finish. From my rule of thumb calculations this would give a sound reduction in excess of 60dbA. Obviously there would be further sound reduction of the solid walls through to number 9.