The unmasking of the Atterbury Plot in 1721/22 was regarded as one of the British Secret Service’s most celebrated achievements. Francis Atterbury, the Bishop of Rochester, a High Church Tory side-lined after George I’s coronation, was suspected rightly of Stuart loyalties.

Frustrated by his lack of political influence, Atterbury’s hatred of Whig policies became tangible. He excoriated the administration in two anonymous pamphlets, the first of which contained a personal attack on George I.

Atterbury’s belief that only the Tories were able to restore High Church Anglicanism to the centre of English society allowed him to be persuaded to support the Pretender with the aim of reinstating a Tory government and restoring himself to influence and power.

During the public outcry that followed the collapse of the South Sea Company’s share price amid widespread evidence of fraud, Atterbury began a correspondence with Jacobite agents and developed plans for an insurrection. Various proposals were debated but the strategy finally chosen centred on an invasion force of Jacobite regiments in the service of the French and Spanish armies which would catalyse general uprising led by Jacobite sympathisers within the Tory aristocracy. Key buildings in London – the Bank of England, the Tower of London and the adjacent Royal Mint – would be assaulted and captured.

Although Atterbury later became impatient at the glacial speed of execution and frustrated at the limited funding, he nonetheless remained a central figure in the plot. His correspondence and that of his co-conspirators was monitored by the Secret Department of the Post Office and its Deciphering Branch and passed to the government which moved pre-emptively to arrest those at the core of the conspiracy.

Unfortunately for the government, the main protagonists had been guarded and their letters offered limited grounds for formal prosecution. Given the risk that a court case could be challenged for lack of evidence, the administration chose to subject Atterbury and his associates to ‘Pains and Penalties’ Bills in Parliament with the objective, in Atterbury’s case, of depriving him of his ecclesiastical position, proscribing communication, and sending him into exile.

The Bills were approved by the Commons and Lords in June and Atterbury was exiled. The parliamentary vote hinged on the evidence of decoded letters, many of which were examined at length, with the government’s decipherers called to give evidence in person. Further proof came from France, with a despatch from Paris from Philippe II, Duc d’Orléans, the French Regent, confirming that the Jacobites had requested French military assistance.

Government agents were ordered to the French coast to report on troop movements and to Paris to obtain further intelligence. Concerned that a rebellion was imminent, George I was persuaded to delay his journey to Hanover and the military placed on high alert. Troops were recalled from Ireland. Regiments of Foot Guards ordered to encamp in Hyde Park. And regiments of Horse and Foot repositioned south from Scotland and billeted on Salisbury Plain, from where they could be despatched anywhere within southern England, and at Hounslow Heath west of London.

With the military in place to put down any putative rebellion, the government revealed on 8 May the ‘traitorous design to overthrow our excellent constitution both in Church and State and to subject a Protestant free people to tyranny and superstition’. The establishment closed ranks and the following day the Lord Mayor and Aldermen of the City of London issued a loyal address that railed against ‘those vile and detestable persons who shall again conspire and attempt to bring a free and happy people under the yoke and tyranny of superstition and to involve this nation in a state of blood, misery and the utmost confusion’.

The ‘design to raise an insurrection in this kingdom in favour of the Pretender’ was lambasted elsewhere, not least by the Middlesex and Westminster Justices who used a loyal address to condemn the Jacobites’ ‘wicked and traitorous designs’ and protest their ‘zeal and affection’ for the king and the royal family.

Alongside these denunciations and protestations the government moved to maintain public calm. Newspaper articles were planted by Charles Delafaye to offer reassurance: ‘we hear that in His Majesty’s German dominions above 21,000 men, all regular troops, are kept in readiness’; a ‘report of the Pretender’s being arrived in France is too ridiculous to be credited’; and regardless of the furore, ‘the Pretender… seems too inconsiderable to alarm us’.

But the administration remained concerned and Horatio Walpole, Robert Walpole’s younger brother, a diplomat and politician, was despatched to The Hague. The press reported that ‘we are assured that Mr Walpole, who receives many expresses from England, hath demanded the auxiliary troops of this state to be in readiness’, and that he had yesterday ‘presented a memorial to the States General desiring them to hold in readiness 6,000 men of their troops to be sent to England’.

With the country roused and the government wary of any secret gathering, Grand Lodge was concerned that the upcoming Quarterly Communication could be misconstrued and sent a deputation to Lord Townshend to obtain his consent for their forthcoming meeting. The London Journal of 16 June 1722 gave an account:

A select body of the Society of Freemasons waited on the Rt. Hon. the Lord Viscount Townshend, one of his Principal Secretaries of State, to signify to his Lordship, that being obliged by their Constitutions to hold a General Meeting now at Midsummer, according to ancient custom, they hoped the Administration would take no umbrage at their convention as they were all zealously affected to His Majesty’s Person and Government.