But regional figures show that some parents still have serious grounds for concern.
Reducing class sizes to 30 or less for all infants was a key Labour election promise. Education Secretary David Blunkett said the Government had made pound;600 million available over three years, allowing education authorities to employ 4,500 more teachers and build 1,600 extra classrooms.
But earlier this year, he conceded that secondary class sizes have grown under Labour. And opposition parties claim that reducing infant class sizes has been at the expense of bigger junior classes.
The new figures, collected by the Government and released this week, are based on an audit of the number of pupils in infant classes taught by one teacher on September 17 (not the number on the register for the class at that time).
The figures show 181,000 infant children were in classes of 31 or more on September 17 - compared to 354,000 in 1998.
Almost 90 per cent of infants were in classes of fewer than 30, compared to only 78 per cent last year. These figures include an estimate of children starting school this term but after September 17, under staggered entry systems.
"The experts agree that it is vital that we focus on infant classes in particular," said Mr Blunkett.
"Secondary classes have an average of six fewer pupils than primaries, and by focusing on the foundations of the 3Rs, we are making the biggest possible difference to the education of children."
Average infant class sizes were below 30 in all 150 English authorities on September 17. However, these raw education authority figures do not include those pupils starting later in the autumn or next year - giving a potentially rosier picture than is evident in schools.
Even these unadjusted figures show that in one area of London - Kingston Upon Thames - more than half of the infants were still in classes of 31 or more.
The London borough was one of 18 areas in which 20 per cent or more of five to seven-year-olds were in big classes, compared to an 11 per cent average for England as a whole. Last year - when the England average was 22 per cent - more than 70 authorities were in this category.
This week's figures only cover infant classes. Statistics for the full range of pupils were collected last January and published in the spring. They showed that junior classes had remained largely the same, with secondary classes increasing slightly in line with a 10-year trend.