The students got the chance to explore famous sets from the films - including Diagon Alley.
They also created photographs of themselves riding in the magical flying car from "Harry Potter and the Chamber of Secrets".
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The actor gave a vivid description of helping a woman give birth in Richmond park in 1963.
The legendary actor said he helped a woman who was giving birth under a tree in London's Richmond Park.
Police want to speak to anyone who may recognise the man.