One difference is in the nature of the foreign currency involved.
Did you know they also have been expected to handle foreign currency?
However, a small black market for foreign currency is still active.
Which is true: we're short of foreign currency, as you know.
But, where possible, take some cash in a foreign currency.
They also found large amounts of local and foreign currency in the office.
They're already getting less foreign currency since the £ was floated.
Then the customer right ahead of you wants to pay in a foreign currency.
People with access to foreign currency are buying even more.
Reserves of foreign currency provide a small return in interest.