50 Pounds Northern Bank

Northern Bank Limited was one of four commercial banks in Northern Ireland licensed to issue sterling-denominated notes under the Bankers (Northern Ireland) Act 1928, a quirk of the UK's devolved note-issuing arrangements that has no equivalent in England, Wales, or Scotland — where only the Bank of England circulates. Northern Bank notes were and remain legal currency, though technically not legal tender even within Northern Ireland itself.

The 1999 series preceded the bank's controversial 2004 robbery by five years, in which approximately £26.5 million in unissued Northern Bank notes was stolen — prompting a full denomination recall and reissue under a new color scheme, one of the most operationally disruptive currency events in UK banking history. This pre-robbery issue was retired as part of that withdrawal.