On 9 June, De Gaulle flew to London and met British Prime Minister Winston Churchill for the first time. It was thought that half a million men could be evacuated to French North Africa, provided the British and French navies and air forces coordinated their efforts.
On the afternoon of Sunday, 16 June de Gaulle was at 10 Downing Street for talks about Jean Monnet's mooted Anglo-French political union. He telephoned Reynaud – they were cut off during the conversation and had to resume later – with the news that the British had agreed.
British Cabinet was reluctant to agree to de Gaulle giving a radio address, as Britain was still in communication with the Pétain government about the fate of the French fleet. Duff Cooper had an advance copy of the text of the address, to which there were no objections.
De Gaulle's Appeal of 18 June exhorted the French people not to be demoralized and to continue to resist the occupation of France. He also – apparently on his own initiative – declared that he would broadcast again the next day.
In his next broadcast on 19 June de Gaulle denied the legitimacy of the government at Bordeaux. He called on the North African troops to live up to the tradition of Bertrand Clausel, Thomas Robert Bugeaud, and Hubert Lyautey by defying orders from Bordeaux. The British Foreign Office protested to Churchill.
On 23 June the British Government denounced the armistice as a breach of the Anglo-French treaty signed in March and stated that they no longer regarded the Bordeaux Government as a fully independent state. They also "took note" of the plan to establish a French National Committee (FNC) in exile, but did not mention de Gaulle by name.
Jean Monnet broke with de Gaulle on 23 June, as he thought his appeal was "too personal" and went too far, and that French opinion would not rally to a man who was seen to be operating from British soil.
On 28 June, after Churchill's envoys had failed to establish contact with the French leaders in North Africa, the British Government recognized de Gaulle as leader of the Free French, despite the reservations of Halifax and Cadogan at the foreign office.