I always treat the audience in two ways: Firstly as if I was just performing to one person - my imagined lover (depending on the intimacy of the moment) - and secondly as if I were in front of friends. I have to appear confident from the moment I step onto that stage, and both these approaches set me at ease. The great thing about Miss Ida Heath is that she is no great beauty, and yet because her expression shows such boundless energy, enthusiasm and confidence her audience couldn't help but be charmed and entertained.
In the lithograph of Yvette Guilbert we see her with her head thrown back as if in ecstacy. Perhaps she's receiving the adulation of her audience, or taking a moment in the full heat of the spotlight to compose herself before singing? I know the feeling so well - the split second in which you have to make the first note of the song count and at the same time capture the heart and attention of the audience. A audience can be a very fickle lover, and if they take no more pleasure from you, it's possible to ‘die’ and wither up there in the blinding spotlight