Serene as ever after a recent hectic trip to Brazil, Pandemonia holds forth on anatomy and the proportions of the ideal body, borrowing my pens to sketch rapid demonstrations.
I marvel at her unlined complexion, never besmirched with a tan or bronzer.
'Look at the back of the picture,' commands Pandemonia: she takes one of my drawings and holds it up to the light the wrong way round. 'It usually looks more free.'
More pictures if you scroll down.