Menaces, Menaces

The first 'menaces' brought Herbert Sipson, professional blackmailer, to the dock, charged with having demanded £10, 000 from a bingo company under threat of bombing their premises. The second is a demand for £100, 000 from the Swallow Sugar Corporation under threat of introducing ground glass into some of its bags of sugar on the supermarket shelves. It, too, bears all the hallmarks of a Herbert Sipson scheme.
But it arrives on the opening day of Herbert's trial and he has been locked up in prison. How can he be responsible?