Milena Wurmer, from Germany, works for Tom Harrison and Catherine Pickstock, who are pro-EU, but are finding it difficult to hire a replacement for her

It is the price that no middle-class family in Britain expected to pay.

The endless supply of enthusiastic (or sometimes rather grumpy) au pairs from Europe to the UK’s family homes is drying up, one of the unexpected casualties of Brexit Britain.

Each year, an estimated 40,000 families offer young foreigners a home, food and pocket money. In return, they get the childcare that allows parents to work, often also forming friendships that last years.

Figures collected by agencies that match au pairs with families show the numbers of Europeans willing to work in UK homes has fallen 40%-50% since 2015.

“Brexit has really damaged us,” said Rebecca Haworth-Wood, chairwoman of the British Au Pair Agencies Association (BAPAA). “Many families rely on au pairs but