Section 88 | Exchange rates.
From legislation.gov.uk
Section 12 of the Finance Act 1899 (fixed exchange rate for foreign currency) shall not apply to instruments executed on or after 1st August 1985, and section 6 of the Stamp Act 1891 (exchange rate at date of instrument) shall apply to instruments to which section 12 of the 1899 Act would apply if this Act had not been passed.