A charity helping victims of domestic slavery says it has seen a four-fold increase in referrals since 2012.
The Salvation Army said it had helped 151 suspected victims in the 12 months before summer 2015, compared with 37 in 2012.
One woman it helped said she had her passport confiscated and was fed scraps from her “employer’s” dinner table.
It is not clear whether the rise is due to greater awareness of existing cases or there are more victims.
Anne Read, the charity’s director of anti-trafficking and modern slavery, said victims were tricked into following their dream and then trapped.