The 65th anniversary of the Battle of Britain is to be marked with a gala dinner attended by the Duke of Edinburgh, 80 veterans and 700 guests.
The Duke of Edinburgh will join 80 veterans for the gala dinner
The Salute to the Few dinner, at RAF Northolt, west London, is organised by the Air League and RAF Museum.
An early morning Eucharist Mass has also been held in Westminster Abbey.
The main commemorations of the World War II campaign will take place on Sunday, with the Prince of Wales unveiling a new monument in London.
Also on Sunday, there will be a wreath-laying ceremony at the official RAF Battle of Britain Memorial in Westminster Abbey, followed by simultaneous thanksgiving services there and at the RAF Church in St Clement Danes, Aldgate.
Prince Charles will unveil the new Battle of Britain Monument on Victoria Embankment, central London.
The RAF was outnumbered four to one by the Luftwaffe
The monument was commissioned by the Battle of Britain Historical Society and funded by public subscription.
Between 10 July and 31 October 1940 the RAF and the German Luftwaffe fought for supremacy over Britain.
It is widely believed that had the RAF - outnumbered four-to-one - failed, the Germans would have been able to easily invade the UK.
Of 2,949 RAF fighter pilots, 515 were killed. Pilots were often scrambled up to five times a day.
In June 1940 France had surrendered, while Russia and the US did not join the war until 1941. Britain stood alone against Hitler's Germany.
In a famous speech at the time, Prime Minister Winston Churchill told Parliament: "Never in the field of human conflict has so much been owed by so many to so few."
Some 515 RAF pilots were killed during the three months
On 15 September 1940, RAF Fighter Command claimed victory over the Luftwaffe after a day of bombing raids ended in heavy losses for Germany.
Shortly after, Hitler postponed and then cancelled plans to invade the UK, turning his attention to the defeat of Russia.