From Joan Grant's Speaking from the Heart:
Should you find yourself sitting on a ghost's lap in a crowded restaurant, as I once did in the grill room of the Savoy Hotel in London, it is better to have a companion who can warn you if you talk to it too loudly, otherwise you are liable to startle the waiters. This ghost was feeling exceedingly lonely, for there were no guests at his table. So I sent out an urgent call for his friends to come share it with him. In a couple of minutes six of them turned up, and to me seemed so solid that I was surprised that no one else saw them. Only when I was leaving the restaurant did I notice that there was a small brass plaque on the pillar immediately behind my chair. On it was inscribed: "This table was regularly used by Charles Frohman for many years up to 1915."
I suppose it was a kind of heaven for a fragment of his personality. For, as I later discovered, he did not die there but was drowned on the Lusitania.