David Cameron has once again cheekily invoked the Chartist democracy movement from the 1830s and 1840s as a justification for his boundary changes. The Chartists did indeed demand equal constituencies, but there was no banner at Kennington in 1848 reading "Equal constituencies for all! No variation of more than five per cent in registered electorate (with the exceptions of the Isle of Wight, Orkney & Shetland and Na h-Eileanan An Iar)". Even after the Great Reform Act of 1832 there were still differences in constituency electorate of the order of 100:1, and huge systematic differences between industrial areas and market towns. It is insulting to compare the previous work of the Boundary Commission, which has produced more or less equal constituencies, with the grotesque differences that existed at the time of the Chartists.

When the Chartists complained about unequal-sized constituencies, they were thinking about gross injustices like the 243 electors of Andover in Hampshire having two MPs between them in 1847, the same representation as the 23,630 electors of Lancashire (Southern). A few odd cases like the Isle of Wight and Orkney & Shetland are hardly in the same league. The "Chartist" argument also ignores the differences between adult population and the number of people on the electoral register. This was, of course, enormous in 1847 – but more or less a match by the 1970s. Since then, particularly since 2000, there have been increasing numbers of people left off the electoral registers – this time not through deliberate legal disqualification but because the machinery cannot keep pace with the speed at which some people move house, and the alienation of young people in particular from any official channels. Cameron’s intentions have very little to do with progressive political reform.

The problem of the difference between registered electors and the real number of people in a locality entitled to vote is acute. The worst-affected are the young, the poor and socially marginal; already in 2010 the average Labour constituency in England probably had more people qualified to be on the register than the average Tory seat. This is likely to get worse, because a more complicated and expensive system of individual electoral registration is being introduced from 2014. The government’s new law on boundaries requires a disruptive boundary review every parliament, and the next one may take place in 2015 on the basis of particularly inaccurate electoral registers.

It is worth recapitulating what the new boundaries mean, and how they compare internationally. Other than in a few exceptions granted for islands, constituencies will now have to be within five per cent of the UK average size, i.e. between 72,810 and 80,473 electors on the register in December 2010. This may sound reasonable, but it is the most extreme implementation of "equal size" in a national legislature that uses single-member districts.

There are two broad dimensions to equalising constituencies.

• What to do with the anomalies – islands and national minorities – and how many particularly small or large constituencies should be tolerated because they are special cases.
• The level of uniformity imposed on the majority of "normal" cases.

The government’s bill requires that over 99 per cent of constituencies are within five per cent of the national quota (the exceptions being two Scottish island seats and perhaps one in the Highlands). No other comparable legislature hits 90 per cent. In terms of the overall deviation from the standard size, the government’s proposal is twice as "equalised" as the US House of Representatives.

It is worth asking why, despite legal and constitutional rules about equality, Australia and the United States fail to equalise their constituencies.

The answer is that both countries respect the boundaries of their component states and territories when drawing national legislative districts. Australia divides its 150 House seats into eight states and territories, and the US House of 435 is divided into 50 state delegations. Some states in each country are small – seven American states have single seats, and five more an allocation of two seats. The result is that Montana comprises a single Congressional district of 994,416 people, while the slightly bigger state of Rhode Island has two small districts with around 527,623 people in each. Ten voters in Rhode Island have the same voting power as 18 Montanans – a bigger variation than the divergence Nick Clegg called "deeply damaging to our democracy" back in 2010. I am pleased that he seems to have changed his mind.