Sharon Penzer, who found herself on the receiving end of the unmistakably hostile glares, said: "It is assumed that these are your children and you should deal with it. There is no understanding of what the child's been through." Sharon, 35, and her husband Steven, 42, who live in Birmingham, have fostered 50 children in the past five years but stopped taking in babies when they found themselves and their own daughter becoming too attached to them.
"We had one child who was only six weeks old when she arrived and it was like a bereavement when she left," says Sharon. "I still get quite choked about her and it's been a few years."
The agony of having to part with children that you have taken into your home was highlighted last week when a foster couple ran off with the two little girls in their care. It seems Jeffrey and Jennifer Bramley were worried that their application to adopt the children was about to be turned down.
The children's natural mother immediately issued an emotional plea for their return, stressing that she had not given up the children because she didn't love them, but quite the opposite. "I did it because I loved them and I wanted them to have a nice family to live with," she said.
"Abduction is extremely rare," according to a spokesman for the National Foster Care Association. "A lot of trouble is taken to stress to carers that there are problems with forming attachments to children, but essentially your job is to work to support the child at a very vulnerable time in their life and try to ensure as far as possible that they retain a strong bond with their family in the hope that they can go back to them."
Colin Green, Assistant Director of Children's Services at Cambridgeshire County Council, where the Bramleys lived before their disappearance, acknowledges that fostering is hard on both the foster carers, who suffer "pain and heartache" when the children leave, and the natural parents who often feel jealous at the sight of someone else looking after their children.
Sharon and Steven Penzer now take in three- to ten-year-olds, a situation they find slightly easier to cope with as the children recognise that they are not their parents. "A lot of the children we have have been severely abused and they do talk about it, usually at the breakfast table. They say: 'I've been locked in cupboards','I've been force fed'. They need to talk about it because for them it's the norm and they want to see your reaction, to see how you feel."
Sharon Penzer, who has completed the National Vocational Qualification in foster care, is very aware of the need to create a stable environment for the children she takes in. "By living with you, they see it's normal to have food on the table and to play with toys, it's just creating something they're not used to."
An alarming number of the children who have stayed with the Penzers have not known how to use a toothbrush or even the toilet, and these are children as old as eight.
As for Lauren, their eight-year-old daughter, feelings of jealousy are inevitable, and at the sight of all these other children coming and going she often asks 'when do I move on?'. Sharon says she is often tempted to adopt. But, she says: "We're fostering to help children move on and to help them make a better life. As long as I keep bearing that in mind I'll carry on and not adopt."
Of the 60,000 children in care in the UK, two thirds are placed with foster families which have increasingly come to replace children's homes, the subject of so much criticism in recent years. Foster carers are thoroughly vetted, police-checked and given extensive training to prepare them for what lies ahead.
Ernie Flynn and his ex-wife Pru used to provide short-term emergency foster care in London but stopped due to a disagreement with the local authority. The couple had five children of their own but when their youngest reached 14 they decided to start taking in others on a foster basis. "We first started off with 14-15 year-olds," says Ernie, 59, "but they are very difficult when they're that age, they've got their rights and they say 'I want to smoke, I'll smoke when I want'."
The family then took in seven and eight-year-olds who had been "sexually abused or burnt with cigarettes, hit with hammers and all sorts of things". After that they took in pre-adoption children, including babies that had been abandoned. Ernie remembers the "emptiness" he felt with each child's departure, but he still sees those he built up a particularly close bond with.
Foster carers often keep in touch with children who have passed through their homes, although sometimes they have to force themselves to let go.
"You have to be careful not be extra baggage for them to carry around," says Deborah Gibbs, 38, who has been fostering children for the past 14 years in Guildford. "If you're luggage, you're useful and there are things about you they can make use of. But when you're extra baggage around their necks forget it, they don't need it"
All carers have their own way of dealing with the trauma of children moving on and Deborah Gibbs, who has three teenage children of her own, copesby throwing a party for them.
"What's really important when your children move on is that you have a proper good-bye and you finish it, you close that chapter and move on.
"We usually have an event that marks it, with a cake and a pressie and photographs, and say: 'This is what it was all about. This is why you were here.' It gives them something good to take away and I think it's as important for the fostering family as it is for the child."