Hi Miriam and I'm very grateful for your input, as ever.
Here's some clarification:
One business is a cookery school offering educational services - the other business is a restaurant open to the public, run by the students of the cookery school (both are owned by the same company).
The company in question has been using the same address for both - 24-27 Castle Mews - t**he business names and phone numbers are different. **
So all seems OK at the moment. I could keep their shared address as it is, which is accurate.
However, it is also clear that each business actually has a distinct address within Castle Mews, so if I wish to differentiate/split the addresses, so each business has a distinct address, I can:
The restaurant is at 24-26 Castle Mews - the cookery school is at 27 Castle Mews, so does it make sense to split the addresses along these lines, or doesn't it really matter?
Look forward to hearing from you, Luke