Alec - Apart from the record title and the date , you are correct
The FIRST Skiffle hit was Rock island line / John Henry in 1955 , which was relased as The Lonnie Donegan Skiffle Group while Lon was still playing with Chris Barber's band , with Chris Barber on Double Bass and Beryl Bryden on washboard .
Dont You Rock Me Daddyo was never released as a single ,in fact .