Just bought a property that has a dog grooming parlour on the ground floor and I want to convert the 1st floor to a flat. Without disturbing the business down stairs or ripping up the floor boards on the 1st floor, how do I provide 60mins fire protection between the 2?

Thanks in advance.

You can't - there is no 'magic barrier' - either apply a solution from above or below. Or install a full BS5839-1 (not domestic) fire alarm system to the ground floor with call points, sounders and detection that also has sounders in the flat and operate a full evacuate policy for the whole building.