TBH I can't provide many details yet but....
1) Probably between 3 (that are currently known) and... lets say 10 properties possibly including flats, shops and houses.
2) They were purchased a long time ago, at least 5 anywhere up to 30 years ago...
They are all London addreses in Greater London (I think) which will suggest possible prices...
As I said the whole thing is based on murky details but the individual form whom it was inherited has had a fair number of properties for quite a while, whether they remain and what legal state they are in will become clear later.