English Civil War cipher belonging to Cromwell ally goes on display

A cipher belonging to an ally of Oliver Cromwell early in the English Civil War has gone on display for the first time.

The document, dating from the 1640s and rediscovered only last year, is being featured as part of a new exhibition on spying at the Cromwell Museum in Huntingdon, Cambridgeshire.

The cipher was found recently among the papers of the Parliamentarian general Edward Montagu, 2nd Earl of Manchester, who lived at Kimbolton Castle, also in Cambridgeshire.

The Civil War cipher belonging to Edward Montagu, Earl of Manchester. By substituting letters for numbers, it was indecipherable for those without the key. Image: Huntingdonshire Archives 

The Earl, a fierce critic of King Charles I, was commander of the Eastern Association army from 1643, securing the region for Parliamentary forces. Cromwell was initially Montagu’s second-in-command, but later helped bring about his resignation after perceived failures following the Battle of Marston Moor, which Parliamentary forces nonetheless won, on 2 July 1644.

Following Cromwell’s reign as Lord Protector and the collapse of the republican state that existed briefly after Charles I’s execution, the Earl came full circle and was advocating for the restoration of the monarchy. He served in several roles at the court of Charles II before his death in 1671.

The cipher was only rediscovered last year in the papers of the Huntingdonshire Archives. It had faded so badly that digital alteration by archivists was necessary to make it legible.

The exhibition in which it features, Secret State: Cromwellian Spies and Intelligence, provides ‘an insight into the murky world of espionage’ during the time of the Civil Wars, its curator Stuart Orme has said.

‘The exhibition shows how ciphers and codes were used, how letter-locking was deployed to stop people breaking into letters or to reveal if the letter was obviously tampered with,’ he added.

Other items on display include a dagger on loan from the National Civil War Centre in Newark and a coded letter written by the Queen Consort, Henrietta Maria, to her husband Charles I in 1643.

This letter was among those captured by the Parliamentary side after the Battle of Naseby in 1645, a significant defeat for the Royalists. Also displayed is a recently donated copy of a pamphlet by a disillusioned former colleague of Cromwell, which called him a tyrant and discussed up to five assassination plots ‘each of which proved more catastrophic than the last’.

The museum, which celebrated its 60th birthday last year, tells the story of Cromwell from his childhood in Huntingdon to his death as Lord Protector in 1658. Housed in his former school, it contains nearly 1,000 objects relating to him, making it the most extensive collection of its kind in the world.

Secret State: Cromwellian Spies and Intelligence runs until September 2023.