Section 251(1) does not apply in relation to a gain accruing to a person on a disposal of a foreign currency debt (or an interest in such a debt) unless that person is—
an individual,
the trustees of a settlement, or
the personal representatives of a deceased person.
A "foreign currency debt" is a debt—
owed by a bank in a currency other than sterling, and
represented by a sum standing to the credit of an account-holder in an account in that bank.