It said most parents would be exempted but those who babysit for more than two hours at a time, or more than 14 days per year, should be registered.

The “reward” could be money or free baby-sitting in return, it said.

It comes after Ofsted told two police women to end an arrangement to care for each other’s children.

According to the Mail on Sunday, Ofsted told two detective constables, Leanne Shepherd, from Milton Keynes, and Lucy Jarrett, from Buckingham, to end their arrangement.