A few weeks ago, Duncan Seddon had a cup of tea with the new Rio Tinto chairman, Jan du Plessis, who was in Australia to canvas opinions on Rio's proposed Chinalco deal (it has since been scuttled in favour of a BHP joint venture).

Seddon is not a major Rio shareholder. Nor is he an influential fund manager or mining analyst. Instead, he represents the Australian Shareholders' Association (ASA), made up mainly of mum-and-dad investors who run their own super funds.

"We asked to meet him and he agreed," says Seddon, 60, who is the ASA's volunteer monitor for Rio Tinto and BHP. "That is testament that we do have some say."

He took the opportunity to remind du Plessis of retail shareholders' concerns about the Chinalco deal. And he told du Plessis that the ASA was unhappy with the lack of mining expertise on Rio's board of directors.

Seddon concedes that his annual chats with Rio and BHP chairmen do not stimulate instant action from either of the companies.

"At the end of the day, all the chairman has to do is keep the top 20 shareholders happy," he says, adding that the meetings are always cordial. "We tell them how we're going to approach things and we usually then agree to disagree."

So what's the point of the meetings and all the unpaid time Seddon spends monitoring ASX announcements, attending analysts' briefings and preparing reports on how the ASA should vote its proxies at the annual general meetings?

"It's the constant drip, it's the constant nag. And we get up at the AGM and say it in public," he says. "It's contributing to the pressure on companies to make sure directors are competent and have the time to do the job properly."

Seddon's background as an industrial chemist and adviser on the economic viability of oil and gas projects gives him an understanding of what companies such as Rio and BHP are doing.

He grew up in a Lancashire mining village, where his academic results were good enough to get him a spot in a selective grammar school.

"That stopped me from becoming a window cleaner like my father, or a coal miner, or joining the army," he says. "You moved from being working class to middle class, essentially."

At Sheffield University he completed a degree and PhD in chemistry before working for ICI as an industrial chemist in England then, from 1980, in Melbourne. He moved to BHP's Melbourne research laboratories in 1982 and in 1988 set up a consulting business, which was based at Mount Eliza, an hour south-east of Melbourne.

Seddon's involvement in the ASA came about because he had run his own super fund since 1992 and was interested in the sharemarket.

He joined the ASA in 2000 through his local Mornington group, then four years ago he volunteered to monitor BHP, Rio Tinto and Oxiana (now known as OZ Minerals).

He emphasises that the ASA does not give financial advice on which shares to buy; rather it concentrates on corporate governance issues based mainly on the composition and competency of a company's board.

Seddon's volunteer role takes about a week of work each year per company, although he has recently been devoting a day a week to the task. "I hope to spend less time in future because I hope these companies stop dropping clangers," he says.

Australian Shareholders' Association asa.asn.au.

The big questions

Biggest break When I first started consulting [on oil and gas projects], I was 39 or 40, I had debts, kids, etc. My first job was for Alan Bond, doing an economic evaluation for Bond Petroleum on a gas project. He paid me so much, I paid off my mortgage. Once you've got no debts you are much freer and you can survive.

Biggest achievement I'm still here [working for myself] after 21 years and I enjoy what I do. I do not see myself retiring.

Biggest regret I tend to just walk away and say: "Oh well, that's not worked." I don't tend to rake over past failures.

Best investment The government selling me stuff that it didn't know was worth so much. I bought CSL [the former government-owned Commonwealth Serum Laboratories] at $2 a share and sold out at $25. And I bought Tabcorp for $2 it went to $14 and has paid a lot in dividends.

Worst investment Centro [Properties]. I bought the Centro story and it turned out to be crappy. I should have listened to the Australian Shareholders' Association monitor, who said their accounts were messy.

Attitude to money We [he and his wife] are not money people. We live very frugally. I still drive a Hillman Hunter 1971 called Florence and I've always grown my own vegetables. We don't go in for buying stuff.

Personal philosophy The classical Christian philosophy do unto others as you would have them do unto you.