There is an au pair drought in the UK. Since the 2016 Referendum there has been a 75 per cent drop in applications by foreign girls to work for UK families. Agencies testify that they can’t find girls for their clients, who must turn to other forms of childcare beyond the rare girl keen to ‘learn English’, grandparents, if they can be dragged out of restaurants, and baby-sitting apps like Bambino, Bubble and UrbanSitter.