This is a slightly different approach but bear with me...
Try and get the phone number of the deceased, off of one of his old customers.
Phone his wife and explain the situation.
I would offer to buy his round (there is probably a record somewhere) and take pot luck.
More importantly (and this happened to me).
Offer to sort out all the customers and take on any new enquiries to his mobile or landline.
I was offered a round for free, (she approached me)
The wife was so upset with people calling (asking where the window cleaner was) or new customers, she couldn't deal with it.
I contacted every single customer so she could have some...peace!
The irony here is that the small round was an absolute crock of crap and I wasted a lot of time.