Here’s what Roberts says about British Government involvement in the Cadoudal plot to assassinate Bonaparte:

In the early hours of August 23, 1803, a Royal Navy intelligence officer, Captain John Wesley Wright, secretly landed Georges Cadoudal, a Dr Querelle and a small number of other Chouans at Biville in Normandy. Wright next landed General Charles Pichegru (...) along with seven co-conspirators at Biville on January 16, 1804, and returned to Walmer Castle in Kent, where British naval intelligence was based. Wright was acting under the orders of Admiral Lord Keith, commander-in-chief of the North Sea Fleet, who reported to Admiral Earl St Vincent, the First Sea Lord. St Vincent’s own orders from Lord Hawkesbury were that it was ‘of the utmost importance that Captain Wright should be involved in the fullest latitude’. Other documents, including one from Keith specifying that Wright ‘is employed on a secret and delicate service’, connect the British government intimately with the Cadoudal conspiracy, at the highest levels of both.

Further evidence of direct British government involvement in the 1804 plot to murder Napoleon lies in several letters, the first written on June 22, 1803, from a Mr Walter Spencer to Lord Castlereagh, a senior British cabinet minister, asking for the repayment of £ 150 for himself and £ 1,000 for Michelle de Bonneuil, a royalist plotter with several identities who is known to have met Louis XVIII’s brother the Comte d’Artois (the future King Charles X) in Edinburgh during the Amiens peace. Spencer said the money had been advanced ‘relative to a political intrigue planned by Lord Castlereagh to abduct Bonaparte in 1803’, which was co-ordinated by Mr Liston, the British envoy to The Hague (38) (Plots to ‘abduct’ Napoleon at this time were transparent covers for his assassination.) Although there is nothing directly incriminating from the government side in the exchange – as might be expected – George Holford, a member of parliament who was Castlereagh’s closest friend in politics, wrote to Spencer saying that if he would ‘take the trouble of calling in Downing Street his Lordship will see him upon it’. This would hardly have been the case if Spencer had been a crank.

38-NYPL Napoleon I folder 1

Roberts, Andrew (2014-10-02). Napoleon the Great (pp. 333-334). Penguin Books Ltd. Kindle Edition.