Johnny Depp thrilled children at a London school on Wednesday - by making an unannounced visit, dressed as his "Pirates of the Caribbean" character.

The star is currently in the U.K. capital filming the latest adventures of Captain Jack Sparrow in the next instalment of the franchise, "Pirates of the Caribbean: On Stranger Tides," and he took time out from his busy schedule to visit Meridian Primary School in Greenwich after receiving a letter from pupil Beatrice Delap asking for help staging a "mutiny" against the teachers.

The note to Depp read, "Captain Jack Sparrow, At Meridian Primary School, we are a bunch of budding young pirates and we were having a bit of trouble mutiny-ing against the teachers, and we'd love if you could come and help."

And the nine year old was delighted when her big screen hero visited the school and walked in to the school's assembly in full costume.

Delap says, "He gave me a hug and he said, 'Maybe we shouldn't mutiny today 'cos there are police outside monitoring me.'"

Depp is well known for treating children to special visits dressed as his beloved "Pirates" character - last year he thrilled young patients at Great Ormond Street Hospital in full costume.

Click for more great Johnny Depp pictures: