A lot of these ad's dont meet the UK Gov definition of an Au Pair
copy and pasted
They?re treated as a member of the family they live with and get ?pocket money? instead - usually about £70 to £85 a week.
Workers and employees have different rights, eg the right to the National Minimum Wage and paid holidays.
Au pairs may have to pay Income Tax and National Insurance, depending on how much pocket money they get.
An au pair isn?t classed as a worker or an employee if mostof the following apply:
+they?re a foreign national living with a family in the UK
+they?re an EU citizen or have entered the UK on a Youth Mobility Visa or student visa
+they?re here on a cultural exchange programme
+they?ve got a signed letter of invitation from the host family that includes details of their stay, eg accommodation, living conditions, approximate working hours, free time, pocket money
+they learn about British culture from the host family and share their own culture with them
+they have their own private room in the house, provided free of charge
+they eat their main meals with the host family, free of charge
+they help with light housework and childcare for around 30 hours a week, including a couple of evenings babysitting
+they get reasonable pocket money
+they can attend English language classes at a local college in their spare time
+they?re allowed time to study and can practise their English with the host family
+they sometimes go on holiday with the host family and help look after the children
+they can travel home to see their family during the year
...end quote.
The bit I find interesting is that they 'help' with light housework and childcare for around 30 hours a week INCLUDING babysitting