COMPLAINTS about au pairs often concentrate on the length of time they spend on the telephone and in the bathroom.

However, there may be more serious issues involved such as helping young children deal with the sudden departure of Rosaria and the imminent arrival of Conchita.

"Au pairs come here to learn English, and as such they tend to follow the academic year," says Mary Kelly of theu Pnir Bureau of Ireland. "So they arrive in September and leave in June. Then you will get the older graduate coming just for the summer months, and these will be placed with families who have older children or where a mother is working for the summer and wants back up.

"I explain to families that the settling in period can be difficult. The new au pair is coping with homesickness, culture shock, language difficulty. The children will have to get used to her while still pining for her predecessor. There is nothing you can do about this."

Judith owns a boutique in the midlands, while her husband works away from home a lot, they have a boy aged six and a four year old girl. Judith began using au pairs when her children were tiny, because she wanted a continuum of care at home.

"Our relationship with the au pair goes through a kind of cycle. She arrives, it takes a while for her to settle in, the kids, particularly my son, may be upset, there may be a few spats as we get each other's measure - then the kids absolutely love her and we're into the honeymoon.

"They are very sad after she goes - and then the whole cycle begins again. We try to prepare them as much as possible by explaining that the current girl has to go home but - she will come back and see us again (and one has done this). We also talk up the new girl: `she'll be absolutely lovely'. We have her photograph, they speak to her on the telephone, they're all excited in advance.

"We had a disaster last autumn when the new girl lasted only a month. She just didn't settle - she was very withdrawn, and I would come home from work to find her with a face on her, and the kids upset.

"We had to decide how long to stick with it, and we finally cut our losses, let her go, and started again with someone that they could begin to relate to."

Mary Kelly says it's quite rare for arrangements to fall down. "What is more common is that a girl feels she's learned enough English and wants to go home say after six months. Sometimes she hasn't the maturity to give notice to a family and instead leaves precipitately, which obviously causes a lot of problems."

Patricia Murray, author of Choosing Childcare, says that a disadvantage of an au pair as childminder is the short duration of stay, which means that children have a succession of care givers.

"Children may think they have done something wrong if the au pair leaves. They should be made aware that the au pair will be going back to her own family eventually. They will accept the departure better if they know at the outset that her stay is for a limited period."

This presupposes a child is old enough to have a concept of time. Psychotherapist Mary Paula Walsh of Turning Point says, "If a child has had good early experiences, has bonded well with her mother, then the primary relationship is healthy and even though all day is spent with the au pair, her mother remains still number one - which helps when the au pair goes."

Even so, the sudden leave taking of a significant adult in the life of a young child can be traumatic: "It is like a bereavement," Walsh says. "If the child is old enough, I think parents should talk about the fact that the au pair will be going and begin to prepare the child.

Part two of the process is accepting the new minder. "Ideally a parent needs to take some time over the transition from one au pair to another rather than going off into work and leaving the new girl with the kids for the whole of her first day. The new girl will also need support. She needs time with the parent, without the children, to explain how she is getting on."

Public relations consultant Mary Murphy and her husband Rory have been through such a transition with their three small children, but she is reassuring about the consequences. "I think children can be upset when someone leaves, but mothers can - out of guilt - make more of it than they should. As long as children are generally secure, I wouldn't overestimate it. Children are tremendously resilient."