There are two issues of trust at stake in this general election. One is the question of whether we can trust the parties and their leaders to keep their promises. The other, which has more far-reaching consequences, is whether we can trust the electoral system itself. The evidence, on the basis of last week’s astonishing revelations about the scale of postal voting fraud, is that we cannot. Worse, as we reveal today, Labour is conniving to undermine the system by ignoring warnings about the scope for abuse. It has failed to curb fraud by tightening the rules.

We had come to trust our electoral system in Britain. We rightly scoffed at the gerrymandered polls passing themselves off as democratic elections in Robert Mugabe’s Zimbabwe or Saddam Hussein’s Iraq. We had fun with the hanging chads in Florida that prevented the result of America’s 2000 election being declared for weeks. Electoral abuse in Britain was surely something that came and went in the era of the election of Eatanswill in Dickens’s The Pickwick Papers.

Sadly, that was too complacent a view. Under new Labour, thanks to a policy of deliberately encouraging postal voting, parts of Britain’s electoral system would, as a judge graphically put it last week, “disgrace a banana republic”. The judge, who identified 15 different types of fraud involving six Labour councillors in Birmingham, described postal voting as “farcical”, “hopelessly insecure”, containing “no effective safeguards”, and “an invitation to fraud”. In Blackburn on Friday Mohammed Hussain, another Labour councillor, was imprisoned for more than three years for obtaining and forging more than 200 postal ballots. Police are investigating cases of similar abuse in at least seven other places.

Labour tries to pass these off as isolated incidents, insisting that the system is secure. That, however, will not wash. Our YouGov poll today finds a serious erosion in trust in our electoral system: fewer than a quarter trust it “a lot”. Most say their confidence in the integrity of the system has been knocked; a quarter say there are major abuses and that they do not trust it at all. As for what should happen next, a big majority believes that postal voting should be stopped until security has improved.

Why, then, is the opposite happening? Since coming to power Labour has transformed postal voting. The original idea was to help voters who had real difficulty getting to the polling station. Now it is a means of bolstering the party’s vote. Party documents proclaim that postal votes are Labour’s best friend and supporters with postal ballot papers are four times more likely to vote. This does not mean every postal vote is fraudulent. But without proper safeguards in place the scope for fraud is massively increased. Nearly 3m people have registered for postal votes for this election. That number will rise over the next fortnight. In 1997, 740,000 used postal votes. On May 5 the figure is likely to rise to as high as 4m, or 15% of votes cast. In some constituencies the number who have registered to vote by post has increased tenfold.

This is despite the fact that ministers have been made well aware of the scope for fraud and abuse. Postal ballot forms can be sent to any address and be completed by anybody. The unscrupulous can request postal ballots for dead or non-existent people, often with little fear of getting caught. Postal votes are easily intercepted because, as the judge in Birmingham said, short of writing “steal me” on the envelopes, they could hardly be less secure.

Last year the Electoral Commission called for postal voting procedures to be tightened up. A cabinet committee discussed such changes but rejected them, fearing they would reduce turnout among Labour voters. What is Labour’s problem? The electoral system is skewed so much in its favour that even a two-point Tory lead in the popular vote would leave Labour as the largest party in the House of Commons. The Tories need to be a staggering 10 points ahead to be guaranteed an overall majority.

Yet still Labour refuses to take action to restore the integrity of the electoral system. For that it deserves to be punished.