Sir Tim Chessells is not used to an easy life.

His last job, chairing a body charged with putting in place the Tomlinson report's controversial health care reforms in London, can hardly be described as a soft option.

Now, as last week's green paper shifts the target of the government's reforms from the NHS to the legal aid system, Sir Tim will be in charge of overseeing the implementation of Lord Mackay's plans.'It has been tough,' Sir Tim says of his NHS work.

'But it had to happen, and I think in ten years' time people will see that there has been a real improvement in primary health care.'Having taken over from John Pitts as chairman of the Legal Aid Board two weeks before publication of the government's legal aid reform plans, Sir Tim is once again at the centre of protests.

'Most people agree it does not feel right as it is,' he says of the green paper.

'The trick we have got to pull is to have a rational and calm debate about how the proposals can be made to move in the right direction.'One of the most controversial of these proposals is the cap on criminal legal aid.

Sir Tim describes this part of the paper as 'very green'.He draws a distinction between devising a system which effectively budgets criminal legal aid, and the question of whether a cap should be allowed in principle.

'Of course people must have access to justice on criminal matters.

You may well manage, control and budget expenditure very carefully, but you may well not end up with a cap.'As far as the general debate on Lord Mackay's proposals is concerned, Sir Tim suggests the contested election for President of the Law Society has not come at a good time.

*'It's probably the worst time for the Law Society to have a debate about the green paper,' he says.

'There is a contested election for President which the Society has to get on with.'But Sir Tim stresses that there is a consensus that the growth of legal aid expenditure cannot be limitless.'We have got a significant and growing piece of public expenditure,' he explains.

'We have got apparent agreement that the proportion of GDP that goes on public expenditure has to go down if it goes anywhere.

Arguments that start from the point "this is only 1% of public expenditure so it could quite easily be higher" are nonsense.

The key point is that it is a lot of money - a lot more than it used to be.'He agrees that the Lord Chancellor's reforms should not be implemented in a way that channels money towards a new bureaucracy at the expense of those who actually do the work.

'If you think about it, the nature of a contract should be less bureaucratic than the paper work we are doing now on a case-by-case basis.

One would hope that when we get well into the implementation, and as people get used to it, the need for monitoring will be less.

We must not have something which substitutes bureaucracy for service.'Sir Tim's tone is noticeably tougher when he talks about abuse of the legal aid system.

'In some cases there are people out there doing a wonderful job for their clients, and finding it difficult to get a sufficient reward.

We need to find a way to solve that problem.

But there are some legal aid practitioners, a tiny fraction I am sure, who are getting rather more from the system than is app ropriate for the service they are giving.'It is public money and any misspending of public money is a serious matter.

I think the man in the street would find it difficult to differentiate between fraud and enthusiastic interpretation of the rules.

That is where I am.'Sir Tim does not believe small firms should necessarily miss out under the new legal aid regime.

'We have to concentrate on access and quality.

I am sure there will be a number of small firms who will be providing access, and giving quality.'But he believes that specialist small firms will be in a stronger position than general practices: 'Someone who is an expert in an area of legal aid law and deals with it all the time is going to be quicker than someone who deals with it as part of a general practice.

And he is probably going to do it better.'Responding to Law Society criticism of 'crude cash limits' contained in the green paper, Sir Tim says: 'If you have crude systems and crude controls, of course you may have circumstances where people run out of money.

We envisage contracts where money comes in over a period of time so providers would have some control of the matching of their annual contract against the inflow of need from assisted people.'Regional legal aid boards would keep reserves to cope with 'sudden explosions' of need.

This, combined with an effective implementation of the reforms generally, should, Sir Tim hopes, avoid 'unpredictable results'.

But he is bullish about the LAB's ability to rise to the challenge.

'I think the track record of the board is that we have done things fairly well, and there are lots of other organisations which might make a mess of it before we did.'There are several areas of work now covered by legal aid which Sir Tim believes deserve a closer look.

One of these is disputes between neighbours, another is disputes between tenants and public body landlords.

In the latter case, Sir Tim points out, the public is paying for litigation three times over - for the legally aided tenant, for the public body landlord's legal fees and, finally, to keep the courts running where the case will be heard.'If you look at some of the types of work which we handle, and which appear to be similar, there are very wide variations in cost.'Is it right that dealing with one matter is ten times the cost of dealing with another, very comparable, matter? The argument that there should be some measures to determine the scale of the likely cost of a service is a good one.'Sir Tim will combine his part-time position on the Legal Aid Board with the directorships of a number of private companies, often those dealing in venture capital.

He is a trustee of Chatham Historic Dockyard and the Kent Community Housing Trust.None of the changes suggested in the green paper will, Sir Tim assures, happen overnight.

'Because of the length of cases it will have to be a gradual changeover.

It will not be a case of waking up one Monday morning and finding everything changed.'For the time being, he says,the important thing is the debate - a debate he hopes will be made up of 'rational argument and penetrating light rather than lots of smoke and noise'.