Allingham was the oldest-ever surviving member of any of the British Armed Forces, and one of the oldest surviving veterans of the First World War. He was the last survivor of the Battle of Jutland, the last-surviving member of the Royal Naval Air Service (RNAS), and the last-surviving founding member of the Royal Air Force (RAF). In 2001, he became the face of the First World War veterans' association, and made frequent public appearances to ensure that awareness of the sacrifices of the First World War was not lost to modern generations. He received many honours and awards for his First World War service and his longevity.