Antony Barnett: Little has changed since the scandals of the Nineties

It was 12 years ago when I first used the phrase "cash for access". I was a journalist at The Observer and I had been investigating a clutch of fresh-faced lobbyists who were buzzing around the new Blair government.

Many had been advising the future Labour ministers while they were in opposition and had helped the party get elected. I had been told that some of these so-called public affairs professionals were trading their contacts and privileged access with the new government in return for hefty fees from the private sector.

So in 1998 I asked the American journalist Greg Palast to pretend he was working for a US energy company and approach lobbyists like Derek Draper, Peter Mandelson's old chum, to ask what they could do if we hired them. The results led to the first cash-for-access scandal and shone light into the murky world of political lobbying under Labour.

There are clear parallels with my latest investigation for Channel 4's Dispatches, which shows senior politicians hawking for jobs, bragging about what they can do for any corporate interest that hires them.

Back in 1998, like now, there were boasts of doors to be opened, influence to be gained and privileged access to the heart of government – if you paid the right price. It was the early days of "whiter-than-white" New Labour and there had been promises of a clean-up. So soon after the sleaze-ridden final days of the last Conservative government, there was much talk of lessons being learnt, a new era of transparency and fresh rules to govern lobbying. I, like many others, hoped that a fresh administration with a mandate for change would act.

Little, it seems, has changed.

When the former transport and trade secretary Stephen Byers walked into the hired London office of our fictional US company last month and claimed he was a "cab for hire", it was honestly hard not to be shocked about what unravelled. A hidden camera in a bowl of potpourri captured his claims. As the Dispatches team first watched the recording of the Byers interview shortly after he left, our reaction was genuine disbelief, even among the most experienced reporters of political scandals. For Stephen Byers today, read Derek Draper 12 years ago. Where Draper claimed there were 17 people in the country that counted and he knew them all, Byers offered up his contact book for £5,000 a day – plus, of course, expenses.

As Byers started listing the things he claimed he could do for us – and what he's already done for two large companies – one young researcher shouted: "But he's supposed to be an MP!" It was a refrain heard many times as our team watched one senior politician after another tell our undercover reporter the things they could do for our bogus American company.

The former Defence Secretary Geoff Hoon told us he had been in Washington partly to do something called "Hoon work". When the former Health Secretary Patricia Hewitt started telling our undercover reporter all the many and varied jobs she has at the moment she never once referred to her job as an MP. But then again her outside interests bring in £180,000 a year, almost three times her pay from the taxpayer for representing her constituents in Leicester.

When we began our investigation we decided to approach 20 politicians from both main parties. We threw together a cheap website and hired an office by the hour – but nearly all expressed interest in joining the advisory board of our completely fictional firm. Many got back to us within 24 hours eagerly offering their services. In the end we had too many possible recruits so we invited 10 in for an interview and covertly filmed nine.

Unfortunately the Tory MP Julie Kirkbride, who was forced to stand down after being caught up in the expenses scandal with her husband (and fellow MP) Andrew MacKay, smelled a rat. She informed Tory HQ and a number of our hopeful Conservative recruits sent apologetic emails that they were no longer interested. Kirkbride's warning was too late for the Conservative MP Sir John Butterfill who bragged about his ability to get to ministers, particularly if the Tories won the next election.

One of the difficulties was that it was impossible to know whether what the likes of Byers and Hewitt told us was true. Both strenuously denied wrongdoing – Byers later claimed he was simply guilty of aggrandisement. Viewers of last night's programme can make up their own minds.

So what can be done? The parliamentary body supposed to vet jobs taken up by former ministers is the Advisory Committee on Business Appointments (Acoba). This is supposed to protect the public interest in two ways. First it is meant to ensure that no company gets a commercial advantage by hiring a former minister or senior civil servant, either in terms of influencing policy or winning government contracts. Unfortunately Acoba has no enforcement or supervisory powers. It can merely recommend a former minister should not lobby government for up to two years after he or she leaves office. In practice, this is largely unenforceable as Lord McLennan, a former member of Acoba, has repeatedly made clear.

Clearly, individuals who hold ranks in government are talented and should be able to take up high-calibre jobs in the private sector when they leave. Yet there is now a very strong case for prohibiting all contact between a former minster and government for two years after leaving office. If the individual is really being employed for their strategic thinking and not their Westminster contact book, this should not be a problem. How, then, could this be enforced?

I believe Acoba should be put on a statutory footing. When a minister leaves office and moves to the private sector he should sign an undertaking that he would abide by Acoba's rulings. But not only that. The company that employs a former minister might take a similar undertaking. If it later emerges that these undertakings have been breached then both the former minister and his new employer should face criminal action. A harsh sanction, yes, but if we are serious about stopping the problem highlighted by our Dispatches investigation then this is one way to do that.

With pubic spending facing massive cuts, policy and procurement decisions are worth hundreds of millions of pounds of taxpayers' money. It is vital to get them right.

Lobbying, of course, is part of a healthy democracy. It is essential that corporate (and non-corporate) interests can put their case to government. But it must be completely transparent. Only registered lobbyists should be allowed to contact ministers or civil servants. Meetings between – and minutes from these meetings – should be recorded and released to the public. If a corporate interest has a strong and persuasive case then there is nothing to hide.

When it comes to big business and politics, rules will always be circumvented. There is too much money and power at stake to believe a new statutory committee or register will stop all the problems. But for whoever wins the elections the stakes are high. All the party leaders claim they want to clean up Parliament. If they don't act after this warning, it won't be long before I will be writing or broadcasting about another scandal involving cash for access.

The writer is an investigative journalist who presented last night's 'Dispatches' documentary on political lobbying