When nine-year-old Beatrice Delap wanted to organise a mutiny against her teachers, she knew who to call on.
And it took just one letter to enlist the aid of the world's most famous pirate: Captain Jack Sparrow.
With only 10 minutes warning, Johnny Depp arrived at Meridian primary school, Greenwich, in full high-seas regalia with four other cast members.
Beatrice sent her appeal when she found out he was filming the latest instalment of Pirates Of The Caribbean at the Old Royal Naval College nearby. The letter said: "Captain Jack Sparrow, at Meridian primary school we are a bunch of budding young pirates. Normally we're a right handful but we're having trouble mutinying against the teachers.
"We'd love it if you could come and help. From Beatrice Delap, aged nine, a budding pirate."
Depp strode into the school hall, brandished the letter and called her to the front. She said: "It was the most exciting school day ever. I had the idea to write the letter last week after me and a friend went to see the film set. Pat from the school office delivered it.
"Yesterday the school called us in for a special assembly at the end of the day. They told us there had been a couple of incidents in the playground.
"Then Johnny Depp walked in dressed as Captain Jack. There were gasps and screams. He pulled the letter out of his pocket and said he was going to frame it. Then he called me down and gave me a hug."
Depp, 47, spent 15 minutes performing for pupils and dancing with fellow cast members. "He said the pirates were going to take over the school and only eat candy and our teeth would turn black and fall out," added Beatrice. "But he said we shouldn't mutiny against the teachers because there were police outside and we might get into trouble."
The naval college has been transformed for Pirates Of The Caribbean: On Stranger Tides, which also stars Penelope Cruz. Depp, who was filmed by ITV London Tonight, has reportedly been arriving each day on a yacht after landing in Battersea by helicopter.