1 000 000 Pounds - Treasury Bill

HM Treasury's "giant" and "titan" denomination notes — £1,000,000 and £100,000,000 respectively — are not currency in any practical sense. They exist solely as internal accounting instruments used by the Bank of England to back the value of Scottish and Northern Irish banknotes in circulation. Commercial banks operating in those regions must hold equivalent assets at the Bank of England, and these oversized Treasury Bills fulfill that legal requirement under the Banking Act.

They are never released to the public and never circulate. Surviving examples outside institutional hands are genuinely exceptional.