The custody of very large sums in solid cash entails much care, and some cost; everyone wishes to shift these upon others if he can do so without suffering.
Accordingly, the other bankers of London, having perfect confidence in the Bank of England, get that bank to keep their reserve for them.
The London bill brokers do much the same.

Indeed, they are only a special sort of bankers who allow daily interest on deposits, and who for most of their money give security.

But we have no concern now with these differences of detail.

The bill brokers lend most of their money, and deposit the remnant either with the Bank of England or some London banker.

That London banker lends what he chooses of it, the rest he leaves at the Bank of England.