Khan arranged a domestic service visa and promised to pay her 120,000 shillings (£21) a month into her Tanzanian bank account and £10 a month pocket money in London.

Mrs Mruke, desperate to fund her daughter Zakia's college education, agreed.

But when she got to London, Khan took her passport away, forced her to sleep on the kitchen floor and gave her two slices of bread a day for food. Her clothes were kept in a garden shed.

Between 6am and midnight each day, Mrs Mruke was expected to be at the beck and call of Khan, who would ring a bell when she or her two grown-up, disabled children wanted something.

Metropolitan Police
Sometimes she would even be woken during the night to take Khan's son out for a walk.

Mrs Mruke did not get a single day off in four years.