On the day a parliamentary committee is due to take evidence about the Yarl's Wood immigration removal centre, Simon Cox investigates claims of sexual abuse and poor health care for the women held there. Campaigners and detainees tell File on 4 about "a culture of disbelief" which they say exists among healthcare staff and which they claim is putting women at risk. Serco - the company that runs the centre - insists it provides a good standard of care, but a former member of staff, speaking publicly for the first time, says concerns he raised were ignored by senior managers. The programme also investigates claims of inappropriate sexual contact between staff and detainees and allegations of sexual abuse by staff. Several employees were dismissed last year over sexual encounters with women being held at the centre and the House of Commons Home Affairs select committee have called the managing director of Serco to give evidence about the sexual abuse claims. Simon Cox investigates - and hears why some MPs believe it is time for the centre to be closed. Reporter: Simon Cox Producer: Sally Chesworth.