I suspect there are so many offices become they bring in more rates than housing.
I don't know if there are England/Wales/Scotland/NI differences but in England an office can be converted into flats even if the council don't want it to be so the remaining ones are because the landlord thinks they can make more money that way, not what the council wants.
I don't know if there are England/Wales/Scotland/NI differences but in England an office can be converted into flats even if the council don't want it to be so the remaining ones are because the landlord thinks they can make more money that way, not what the council wants.