“La Fête nationale” The French National Day commemorates the first anniversary of Storming of the Bastille on 14 July 1789, a turning point of the French Revolution, as well as the Fête de la Fédération which celebrated the unity of the French people on 14 July 1790. Celebrations are held throughout France. The oldest and largest regular military parade in Europe is held on the morning of 14 July, on the Champs-Élysées in Paris in front of the President of the Republic, along with other French officials and foreign guests.
Bastille Day has always been celebrated with fireworks since the Fête de la Fédération on 14 July 1790.
London is the sixth biggest French city, so we see many Amis (friends) for the celebration.