For the past six years, Ms Aitken was a partner in a West End firm, concentrating on family law in an otherwise predominantly criminal practice. Ms Kelly worked in a high-street legal aid firm, where she built up the family side of the work. Both women are on the Law Society's specialist children panel, and Ms Aitken is a member of the Solicitors' Family Law Association.
It is undeniably brave, particularly in today's troubled times, to strike out for themselves. Ruefully, they admit to the wrench in giving up the relative security of salaries and company cars, but Ms Kelly brushes aside the 'courageous' tag. She insists that their project has more to do with job satisfaction: the move, both say, was prompted by a feeling of professional isolation. 'We are not in it to make a fortune,' says Ms Aitken. 'It's more to do with working where we want to.'
Historically, family law has been marginalised, Ms Kelly says. It does not sit happily with business aspirations. The City firms, by and large, have closed their private client departments, and in the smaller firms family law tends to be viewed as something that has to be done, and, worse, 'something that anyone can do', she says.
The result is, typically, an adversarial approach which is largely inappropriate in family matters. All in all, family law and its practitioners rarely find support in law firms. 'It's not their fault,' says Ms Aitken. 'It's just the way things develop.' She believes that if solicitors can make a name practising, for instance, criminal law, they will not bother with what they see as sideline issues. In their new practice - which is to be called Aitken Kelly Associates ('We like the initials AKA,' says Ms Kelly) - they intend to act for all parties, including men who have become involved in proceedings arising from violence. This is not to condone violence, Ms Kelly insists, but 'you can't prejudge'. It helps the smooth passage of a case in court if the man involved has a solicitor to balance the proceedings, she says.
Ms Aitken points out that she has in the past acted for men in injunctions against their female partners, adding that these cases also have their pitfalls. 'The men can be embarrassed, feeling perhaps that the action is 'not manly'.'
The arrival of the Children Act on the statute book last October wrought many changes in the practice and procedures of the family lawyer, not least, says Ms Aitken, because it has raised public awareness. 'The most striking thing is the right of unmarried fathers to have parental responsibility, after agreement with the mother. That aspect has had a lot of publicity.'
Equally, people have become more attuned to their rights over children in care. 'Parents now know they can have contact rights (formerly called access), that there is a limit to what a local authority may do,' Ms Aitken says. Grandparents have been brought on to the legal scene, too, with contact rights to their grandchildren written into the legislation.
With the exception of certain spin-off work, such as conveyancing, making wills and duty solicitor shifts, the new practice will not take on anything outside its agreed area. 'We are standing fast on that,' Ms Kelly says.
For the first two weeks, she will work alone at the new premises, 'with a list of things as long as your arm' to do before clients come in. Initially, a junior will be the only office support, although they plan to take on a secretary in the new year. They say they are determined not to fall into the trap, as do many smaller firms, of becoming entrenched in inefficient ways of working. In practical terms this means buying the highest-tech office equipment, from photocopiers to computers.
They are not planning to advertise. Word of mouth, they believe, remains the best way of finding clients. With her departure, Anne Aitken's old firm is ceasing to handle legal aid family law, so she can take willing clients with her, and both women have been promised that recommendations will be put their way.
'We are having a leaflet printed setting out who we are, what we do, and also what we don't do,' Ms Kelly says. This, they agree, is of the highest importance in their bid to corner a part of the family law market.
'In the next 10 years or so, it will become rarer for firms to do everything,' Ms Aitken says. 'It's already happened in personal injury, for example. It is getting much more difficult to dabble.'