Wheatstone & Co. of London built concertinas from 1829 until 1974, and — uniquely in the free-reed world — their production ledgers survive. The Horniman Museum digitised all seventeen volumes, so a Wheatstone serial can be dated from the factory’s own records, sometimes to the exact day a ledger entry was written. This archive turns the ledger indexes into dating ranges: high confidence where the books speak, honest gaps where they don’t.
The record makes room for uncertainty when a precise year is unavailable.
Factory and production era appear alongside the date when supported by a source.
See the source behind a match and what still needs to be confirmed.
The archive currently covers 3 series and 60 dating ranges from 1830 to 1974, compiled from published maker records and reference charts. Coverage grows as new tables are verified.
On Wheatstone concertinas the number is stamped on the right-hand end plate or on an internal reed-pan label. English and Duet models and Anglo models ran partly separate ranges in the 20th century — identify the system first. The exact spot varies by era and instrument type — the serial number guide walks through the common locations.
Recheck the characters exactly as marked, including any letters and leading zeros. Letter-prefixed numbers often belong to student or non-domestic lines that cannot be dated from the number. Some production periods may simply not be covered yet.