It is a problem for M.
Gustave le Bon--a mystery in the psychology of crowds.

The fact emerges that about three o'clock on Sunday afternoon a remarkably big and ugly London crowd, entirely out of hand, came rolling down Thursday Street intent on Bensington's exemplary death as a warning to all scientific investigators, and that it came nearer accomplishing its object than any London crowd has ever come since the Hyde Park railings came down in remote middle Victorian times.

This crowd came so close to its object indeed, that for the space of an hour or more a word would have settled the unfortunate gentleman's fate.
The first intimation he had of the thing was the noise of the people outside.

He went to the window and peered, realising nothing of what impended.

For a minute perhaps he watched them seething about the entrance, disposing of an ineffectual dozen of policemen who barred their way, before he fully realised his own importance in the affair.