Britain's oldest surviving veteran of the First World War toasted his 109th birthday yesterday and shared his secret of life: "Know your limitations".

Henry Allingham, who in 2003 received the Legion d'Honneur, the highest military award that France has to offer, was joining friends for a birthday party in his home town of Eastbourne, East Sussex.

Mr Allingham, who became the first of the nation's veterans to receive the MoD's new Veteran's Badge, is one of only 20 or so surviving soldiers of the Great War.

Yesterday he celebrated his latest milestone at a local hotel with a cake presented by pupils from two Sussex schools.

Mr Allingham, who served in the Royal Navy Air Services (RNAS), fighting at the third battle of Ypres and at the Somme, recalled his earliest memory when, as a toddler, he saw his dying father.

"I went upstairs and peeped through a crack in the door," he said. "I saw my father, who was terribly ill with tuberculosis, sitting up in bed. He was only in his 20s.

"I was hurriedly taken back down and a gate was put up at the bottom of the stairs."

Today, although deaf, Mr Allingham still displays extraordinary mental alacrity, and can recall events throughout his life.

" I can remember the Christmas after the Armistice. I was introduced to two German children, who wished me a happy Christmas and thanked me. I didn't know what to say.

"I had two jaffa oranges with me, which were like gold dust, and so I gave them one each."

Last August, Mr Allingham recalled difficult memories of his role in the conflict before leading the congregation at the Cenotaph in London in the Lord's Prayer to mark the 90th anniversary of the start of the war.

He said: "Like so many, I have tried to forget my time in the war. In the last few years, I have met other veterans, and we never spoke one word of the war." Originally from London, Mr Allingham trained as a mechanic after volunteering for service in 1914 aged 18.

He was sent to the Western Front, carrying out vital repairs to the aircraft, including the Sopwith Camel.