The baby British force, the RAF, was founded on April 1st 1918 and celebrated it's centenary over the Easter weekend.
Although the Royal Auxiliary Air Corp and Royal Naval Air Service operated during World War I, they were merged to form the RAF in the last months of that conflict. Aircraft were used mostly for reconnaissance and the first examples of air combat involved nothing more than acerbic smiles and waves. This escalated to pilots shooting at each other with handguns before machine guns were fixed to planes. The RAF was the first air force in the world to be independent of the other services, and numbered over 20,000 aircraft and 300,000 personnel.
After the end of World War I the relatively new, and still temporary, air force had to wait for nine months to find out if officers would be granted permanent commissions. The Government sanctioned 6,500 officers and the service in total was slashed to 35,500 personnel. The service was given the role of "policing" the Empire but it was with the outbreak of World War II that the service was cemented in the public consciousness.
There was a massive expansion of the RAF in 1939 and with the Battle of Britain and the iconic Spitfire, the fighter pilot command held off the Nazi invasion of Britain through the summer and autumn of 1940. Winston Churchill's immortal words captured the mood of the nation when he said "Never in the field of human conflict was so much owed by so many to so few". The significant contribution of the RAF to World War II was more the Strategic bombing campaigns against Germany. Some of these campaigns have come under fire for the ethics of large scale bombing attacks, like that against Dresden.
The post war era saw the shift toward jet propulsion and the advent of the cold war. The RAF held the UK nuclear deterrent. Known as the V Wing, Three types of large, long distance bombers were the UK front line deterrent until that role was taken over by the Polaris Submarine programme. The Vulcan was to experience an extraordinary swansong in an astonishing series of epic long distance moral boosting raids on Argentinian held Falklands Islands during the 1982 conflict. The raids were named Operation Black Buck and are covered in more detail here The Harriers that flew from Aircraft carriers were Royal Navy aircraft although RAF pilots did fly sorties.
The RAF was inevitably involved in the predominately air attack conflict of the first Gulf War and the Kosovo War in 1999 saw RAF aircraft fight over Europe for the first time since World War II.
The most notable aircraft to have a place in popular British culture in recent years is the BAE Hawk which is used by the Royal Air Force Aerobatic Team, better known as the Red Arrows, along with the Battle of Britain commemorative flight they were responsible for the air displays celebrating the RAF centenary. Curiously, the 50th anniversary was celebrated with gala dinners on the ground, leading to the astonishing event of a No.1 Squadron pilot taking a Hunter jet on a non sanctioned low level flypast over the Thames including a death defying manoeuvre flying through the towers of Tower Bridge.
There are multiple events over the course of the year and not just over the centenary weekend, and more details can be found on the official RAF 100 Website