The above mug sold for more than $1,800.00 recently on eBay.
It is a Royal Doulton, England - OLD KING COLE MUSICAL JUG
Doulton # D6014 CHARACTER (toby) JUG (mug)
Designer: Harry Fenton
Approx. 7 1/2 inches high (referred to as large size)
Playes the tune: "Old King Cole was a Merry Old Soul."
This rare musical tobie was introduced in 1939, and retired (discontinued) in 1939.
Listed on page 303 of The Charlton Standard Catalogue (PRICE GUIDE) of Royal Doulton Jugs, 8th edition (2004): $2,250.00.
It would be a great find if you see one at your local thrift store or at a a yard sell.