Dispatches is set to reveal the worst kept secret in British politics

It is often asserted that the caps imposed on spending during election campaigns mean that the role of cash in politics is simply less of an issue in Britain than on the other side of the Atlantic. As Channel 4's Dispatches programme is set to once again reveal, this comforting story is nothing more than a fairy tale.

Today's Dispatches is reported to document a series of meetings between businessman Paul Wilmott and representatives from all three of the UK's major political parties, including with both Ed Miliband, the leader of the opposition, and deputy prime minister Nick Clegg. Many of these meetings were secretly recorded and will no doubt be of great embarrassment to the individuals in question, even if they do stay within the guidelines set by the Electoral Commission.

How, you might ask, did Mr Wilmott secure such privileged access? To no-one's great surprise, he wafted the prospect of large donations in front of the parties with predictable results.

A series of unfortunate events...

The programmes comes on the back of a number of cash-for-access scandals that have erupted in the run-up to May's General Election. An undercover reporter working for the Telegraph, posing as a wealthy Indian businessman, met with a senior member of Clegg's staff who reportedly advised him of ways to get around electoral law regarding donations in order to allow him to maintain his anonymity.

Moreover, last month undercover reporters from the Daily Telegraph and Channel 4's Dispatches posing as a fictitious Hong Kong-based communications agency also managed to secure meetings with Sir Malcolm Rifkind, who chairs the parliamentary select committee on Intelligence and Security, and former Labour foreign secretary Jack Straw. Both men discussed how they could use their positions to benefit a private firm in exchange for a fee, although they deny any wrongdoing.

What do all of these stories have in common? Well two things actually - both an insight into how access to Britain's top politicians still quite clearly comes with a price tag but also that the only way in which the press appears to be able to uncover this cash-for-access nexus is through subterfuge.

It will come as a shock for very few people that those points where private money meets politics tend to be the murkiest. As politicians jockey with one another for a limited pool of donor cash the temptation to offer more than the other side will always lead a few fundraisers into making promises that skirt, if not quite cross, the boundaries of acceptable practice.

The public interest defence

Shining a light on this behaviour through undercover reporting is a clear case of public interest. Although the set-ups may tread close to what would perhaps constitute entrapment were it carried out by official bodies, revealing those politicians and party members who are willing to cross those ethical lines is undoubtedly a service to the British public. It also (hopefully) discourages such behaviour in future - although the frequency of these scandals may suggests that the learning process is rather slow.

It should be remembered that simply because an offer is on the table, MPs and political parties are under no obligation to accept or even acknowledge it. After all, in the sting that caught out Rifkind and Straw a further 10 MPs were contacted of which six never responded, one refused (saying their contacts were "not for sale") and another said they wouldn't meet until the company in question had been fully vetted.

But the frequency with which journalists have been able to catch people out hints that the problem is both broad and, possibly, insoluble under the current system. At present political parties can spend whichever is the greater of £990,000 or £30,000 times the number of seats being contested. This means a party contesting all 650 seats could, theoretically, spend as much as £19.5 million on advertising and campaigning within the regulated period around an election.

However, the broadcasters miss out on most of that bounty. Under the Communications Act 2003 "advertising of a political nature or directed towards a political end is prohibited on television and radio", according to Bates Wells Braithwaite solicitors. Instead the main broadcasters are all required to offer free party-political broadcasts for each of the main parties and registered parties contesting one sixth or more of the seats up for election - oh and not to mention the exhaustively debated leaders' debates.

Prime Minister David Cameron recently joked that Obama has repeatedly confided to him that "you don't know how lucky you are not having TV advertising". Perhaps, but the costs of running a national campaign are daunting regardless of the advertising rules. And while parties have to raise their own funds, election time is always going to be ripe for undercover reporters to get the ear of hopeful (or desperate) party fundraisers.

The question these journalists need to answer is whether this cash-for-access issue is having tangible policy outcomes. Are these donors winning tax breaks? Are their business interests getting disproportionately prioritised by the new government? If so, then it would be a direct interference in the democratic process and the practice would have to be clamped down on as a matter of urgency.

If not, however, then we may need to revisit what it is about the structure of politics that we have put in place that makes us so uncomfortable with our own system of government. The onus, in other words, would be on the public to either reconcile ourselves with it or to insist on change (including, for example, state funding for major political parties).

In the meantime these undercover stings will continue to drive the headlines. But they may do little to further our understanding.