Candleshoe (1977)

Small-time crook Harry Bundage discovers that the old manor house where Lady St. Edmund resides, with three orphans and her butler Priory is the resting place for a hoard of treasure. Unfortunately, he doesn't know where it is. Bundage recruits urchin Casey Brown to dupe Lady St. Edmund into thinking that she is her long-lost granddaughter, so she can search for clues to the location of the treasure.