Mr Tench, CA's director of legal affairs, has been responsible, directly or indirectly, for an impressive array of legislation, including the 1977 Unfair Contract Terms Act and the 1987 Consumer Protection Act.
He hopes to continue campaigning, however, persuading law firms of the advantages of embarking on political lobbying, or advocacy as he prefers to call it. Mr Tench is surprised that Clifford Chance is one of the few law firms to employ someone in that capacity.
'I would have thought that many London firms, especially the large City firms with huge multinational public company clients, would be very well placed to develop the skills of political advocacy and to put themselves in a position where they could offer a service of representing and promoting their clients' interests to Parliament, to the Civil Service and to the political parties,' Mr Tench says.
The processes of legislation, he points out, have much in common with those of litigation. The practitioner needs to be able to research and assemble a case either for or against; they must understand the law, because for much of the time the political processes are concerned with proposed changes to the law; they must understand fully the political procedures and be familiar with the people involved; and finally, they must be able to present and pursue a case with the utmost skill.
'All of this, I would have thought, would be meat and drink to the legal profession, but there is hardly a sign of this kind of work being handled by firms,' he says. Most of the large City firms have offices in Brussels from where they lobby the European institutions on European political issues, 'but the very same firms would not dream of touching this kind of work when it comes to what is happening in Westminster. I wonder why.'
As a result, he says, CA has never been seriously opposed in its lobbying for the consumer cause in the UK, and this accounts in part for his successes over the past quarter century. Mr Tench joined CA in 1969 after working as an Inland Revenue solicitor. He had already worked for the association on a freelance basis, writing four books including the then definitive Law for Consumers.
Which? magazine had been established in 1957. By the late 1960s, CA decided it wanted to acquire political influence and embarked on a new, structured approach to legal and campaigning issues. Mr Tench had to start from scratch. 'I had no experience,' he says. 'Like all solicitors, I had no idea how to go about getting the law changed.'
He admits to working by trial and error at first, although it did not take him long to identify the fact that an entry point to the parliamentary system was the private members' ballot, for which, his instinct told him, consumer matters were good raw material.
Mr Tench began to learn the ways of Parliament as he nurtured what became the 1971 Unsolicited Goods and Services Act to the statute books. At the same time he involved himself in other political issues in order to establish a firm consumer presence in Parliament.
He quickly learned to be realistic. 'You have to anticipate hostility and make provision for a certain amount of giving ground to your opponents,' he says.
Who actually drafts Private Members' Bills promoted in this way? 'You draft them yourself as you think right, although you must recognise that they will never end up that way,' Mr Tench says. 'The Government will always ensure that Bills are worded in the way they want, and parliamentary counsel never, on principle, accept anyone else's drafting.
'My advice would be to draft in political, rather than legalistic terms. Knock it together is still my approach,' he says. Mr Tench talks about the subtleties of getting a bill through Parliament. 'It is exhilarating,' he says, 'and you've got to keep your wits about you.'
He does admit that his success over the years is due in part to the CA being on the side of the angels. 'It's difficult for the Government to be against issues of consumer rights because consumers are their constituents,' he points out.
The most significant change in the law that Mr Tench has masterminded is, in his view, the unfair contract terms legislation of 1977. 'Lord Denning said it was the most important change in civil law in his lifetime.'
The most exciting political change was probably the housebuyers' Bill that led to the ending of solicitors' monopoly of conveyancing, enshrined in the 1985 Administration of Justice Act. That exercise constituted the most demanding four or five months of Mr Tench's life. Not unnaturally, solicitors opposed the legislation. 'When it got wind of it, the Law Society took against it quite strongly,' Mr Tench says.
'That experience made me realise that lawyers do not understand either the political process or the media. But eventually the Law Society realised it had to come to terms with politics. I am surprised it hasn't seen the value of promoting the idea of lobbying to law firms, although the current president (Rodger Pannone) is interested in the idea.'
Some companies specialise in political lobbying, but as Mr Tench points out, it is not lawyers doing the work, but public relations people or 'ex-MPs whose knowledge of the law is often limited.
'There would be a tremendous advantage in having an understanding of the law you want to change. I would have thought that the major firms would do more about the services they offer to their big clients.'
Barbara Lantin, page 28