I've always known it as 'doodle'. Hugill gives the song title as Doodle Let Me Go, with Alternative title Do Let Me Go, Gels. But he notes "The word 'do' was sometimes sung 'doodle' as Terry gives it; Sharp mentions the fact but gives 'do' in his version, and Harding sang both 'do' and 'doodle' indiscriminately". (He then gives Harding's version with 'Doodle').

Terry gives the title as Do let me go, girls but, as Hugill says, uses 'doodle' in the chorus.

Mick