Keepers, I too wondered if Jono was thinking of Lulu the singer, but then hesitated as 'lulu =smasher' is something very, very dated anyway! I've never seen or heard it used, though I wouldn't be surprised to find it in a Miss Marple story, say.
Etymology sources suggest the usage is perhaps connected to Lulu Hurst (1869–1950), an American stage performer known as the "Georgia Wonder," whose feats of apparent mysterious physical force made her name synonymous with astonishing spectacles. https://en.wikipedia.org/wiki/Lulu_Hurst