25 Pounds White, 1778 issue

The so-called "White Notes" of the Bank of England were handwritten — or partially so — on distinctive laid paper watermarked with the denomination and produced entirely in-house at Threadneedle Street. For most of the eighteenth century, the Bank's cashiers signed each note individually by hand, meaning no two examples are identical in that respect. This was not tradition for its own sake: handwritten signatures were a deliberate anti-counterfeiting measure, on the theory that a forger could not reproduce a living clerk's variable hand at scale.

The theory proved optimistic. By the 1790s, forgery of Bank of England notes had become a serious criminal and social problem, one that would eventually force a complete rethink of note production in the following century. A £25 denomination was substantial — comfortably above a laborer's annual wage — so these circulated primarily between merchants and banking houses rather than in retail trade.