INNOCENT CHUKWUMA, a visiting Nigerian and unofficial election observer, gravely ticks off his worries about the British electoral system: postal and proxy ballots are insecure, and why are voters (outside Northern Ireland) not required to show identification? “If you had this system in Nigeria, the outsiders would say the potential for abuse would be massive,” he says. He should know, having led a team of 50,000 observers who declared Nigeria's 2007 presidential election a charade.

A fellow monitor, Lisa Hanna, a Jamaican MP who happens also to be a former Miss World, frets about Britain's increasingly incomplete electoral register. In the 1950s the register reflected 98% of the adult population; today, it is more like 91%. Inaccurate voters' rolls are the bane of many third-world elections. “In Jamaica scrutineers come to your homes to check,” says Miss Hanna. “We don't act on the basis of trust. Britain has quite a bit to learn.”

Despite such worries, these and other observers organised by the Royal Commonwealth Society will probably declare Britain's elections broadly sound. But they have troubling material to ponder. The Daily Mail this week claimed it had evidence of “massive postal-vote rigging” as police around the country confirmed that they were launching dozens of criminal inquiries. Particularly worrying are east London boroughs, where electoral rolls are said to have been packed with bogus voters. When a journalist from the Independent went to Bow to investigate, a group of Asian men allegedly beat him savagely.

For much of the past century electoral fraud in Britain has seemingly been limited to local elections, in which a few hundred fake ballots are more likely to affect results than they are in general elections. The last time a contest for a Westminster seat was declared void because of malpractice was in 1923. And even at the local level relatively few people have been found guilty of breaking electoral law. Back in 1995 there were 14 convictions for it, the most in any single year before or since.

Yet two trends are troubling. The first is the prevalence of Asians, especially of Pakistani and Bangladeshi origin, among those convicted of electoral fraud. Stuart Wilks-Heeg of Democratic Audit, a research group, points out that British Asians make up half of all those convicted since 2000. Where fraud is most common—such as in Burnley, Oldham, Birmingham—and allegations most persistent there are also large Asian populations. He points to “biraderi”, brotherhood networks, used to rally support for particular candidates—a practice imported from Pakistan. (He also notes that convictions for electoral fraud may be undercounted because some cases are pursued under general fraud laws.)

Such networks may be especially effective at exploiting the other trend: a sharp rise in postal voting. A 2000 law, designed to boost turnout, makes it easy for voters to cast their ballots by post. The share of the electorate who do so has risen from about 2% in the late 20th century to 15% in 2005 and probably above 20% in 2010. In some constituencies it could pass 40% and in certain wards, for example in Oldham, over half of all ballots will be postal. Some constituencies have reported a surge in demand for postal ballots recently.

Thousands of Asian women are disenfranchised by male relatives who take control of their votes.

The most serious allegations of electoral fraud suggest that leaders of biraderi networks, or others, apply for postal ballots for non-existent or ineligible voters and then establish “vote farms”. Residents of one small home in Tower Hamlets, for example, where five adults were previously registered, reportedly applied for an extra seven postal votes in recent weeks. Even where voters do really exist, the suspicion is that network organisers put pressure on people to back a favoured candidate, or complete their ballot papers for them. Salma Yaqoob, a Respect candidate in Birmingham, wants postal voting on demand scrapped because “thousands” of Asian women are disenfranchised by male relatives who take control of their votes.

The Electoral Commission retorts that it has robust measures to prevent fraud, and that the recent surge in allegations is a sign that people think the police will take them seriously. In European and local elections last year 22m votes were cast and 48 complaints made, but there were no “major allegations” of fraud or contested results, the commission says. (Future polls may be safer as individuals, not merely a householder on behalf of others, will register to vote, supplying national insurance numbers to do so). As for postal ballots, rules imposed in 2006 require an applicant to provide a sample signature and his date of birth, which are checked when the ballot is received.

That is hardly a cast-iron protection: anyone registering fake applicants for postal votes could easily supply fake signatures too. But evidence from by-elections since 2006 suggests that the new signature system could lead to more rejections of postal ballots: in some constituencies 8% of them were scrapped, says Mr Wilks-Heeg.

That brings its own troubles. In close races defeated candidates might now claim that unfairly rejected postal ballots cost them victory, raising the prospect of more results being disputed. No one expects bitter fights on the scale of Florida's “hanging chads” fiasco, but wrangling—and allegations of fraud—may dent voters' trust. Mr Chukwuma concludes, quoting Lenin, that “trust is good, but control is better”. He suggests it may be time to reimpose tighter restrictions on postal voters.