Many, many moons ago, the sage detective Charlie Chan traveled to London to solve a mystery. Hanna-Barbera paid homage by sending The Amazing Chan & the Chan Clan to England to work with "Scotland Yard" on a brand new mystery.
A few notes before we go on. As you'll see a 5-piece Chan Clan band performing "Happy" at the start of the episode, you can tell that the movements of Stanley and Suzie were copied from H-B stablemates Josie & the Pussycats. Simply sub Stanley (singing voice provided by Ron Dante) for Josie and Suzie for Valerie, since they both play the tambourine. Len Weinrib was the speaking voice for Stanley, and after wholesale changes were made with the younger Chans, future Oscar winner Jodie Foster was cast as Anne. Henry's speaking voice was done by future primetime star Robert Ito, better known for playing second banana to Jack Klugman on Quincy a few years later.
Actor Jamie Farr (M*A*S*H) served as a writer on this show, as well as the following year's Inch High, Private Eye, but it's curious that he didn't submit any scripts for M*A*S*H.