Guardian Care Homes accuses the bank of mis-selling it an interest rate hedging product linked to the Libor interest rate which Barclays, and other major international banks based in London, are now known to have manipulated.

BBC: Barclays senior staff 'linked' to Libor affair

The bank could meet the requirement by selling at a generous spread over the riskless rate compensating holders for any big risks the bank had taken on.

ECONOMIST: Could banks police each other?

The central bank had tried selling the currency at that level on the interbank market for foreign currency, which is how its exchange rate is normally determined, but gave up when no one would buy it.

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