A dermatologist explains to Rachel Johnson why even though yummy mummies look younger for their age than most of us, their cleaning ladies probably look younger:

“According to a longitudinal study of 1,826 Danish twins, about 40 per cent of the variations in perceived age (i.e. how old you look as opposed to how old you are) are down to environmental factors, and the headline-grabber was this. Yes, heavy drinking, smoking, weight and sun-worshipping have an effect. But they add only a scant year or two to your looks at 70. But being married, non-skinny, with fewer than four children, and in a high socio-economic group (i.e. me), should make you look, on average, a socking 7.2 years younger than you actually are.”

Read on for the punchline.