The Mudlark (1950)

In 1875 London, young Wheeler--who lives by scavenging--finds a cameo of Queen Victoria, which he thinks so beautiful that he risks his life to save it. Possessed of a desire to see the Queen, he slips past the Beefeaters and wanders about Windsor Castle just when a state dinner is in preparation. Meanwhile, Prime Minister Benjamin Disraeli is struggling hard to persuade the Queen to end her long seclusion.