News International-owned thelondonpaper was read on average by 861,000 people each day during the six month period, compared to the 858,000 readers recorded for Associated's London Lite.
Both paper's readership figures were higher than the first figures that the NRS released for the titles back in September, for January to June. Those figures indicated an average 745,000 people read London Lite each day, which was considerably more than the 713,000 people who read thelondonpaper.
Ian Clark, managing director of thelondonpaper, said: "We're delighted that the readership has grown by 20%, although we would still put in a word of caution because we are still to see the sample sizes behind that."
However despite the titles' equal readership figure, Thelondonpaper distributes around 500,000 copies per day, while London Lite circulates around 400,000.
Steve Auckland, managing director of London Lite, said: "Today’s new data shows that London Lite has 2.1 readers per copy compared to 1.7 readers per copy for thelondonpaper.
"These figures demonstrate that our consistent, responsible approach to distribution is continuing to produce strong results."
Associated's other freesheet Metro recorded a 36% rise year on year for April to September, with an average of 2.65m readers per day.
The Evening Standard dropped 19% year on year to 712,000 daily readers, which places it more than 100,000 readers below the two afternoon freesheets.
Among the national titles, The Daily Telegraph took a hit in readership, dropping 11% year on year to 1.97m average daily readers for April to September 2007.
The Guardian had a similar slide and was down 7% year on year to an average daily readership of 1.13m.
The Times was also down 7% year on year to 1.62m daily readers, while its fellow News International title The Sun climbed 2% year on year to post the highest readership figure out of all daily nationals at 7.86m.
Although the Daily Mail dropped 1% year-on-year, it held onto second place with 5.27m readers. Its mid-market rival the Daily Express fell further behind, dropping 6% to 1.61m daily readers.
The Daily Mirror had a positive period, climbing 1% to 3.81m readers, which puts it in third place.
The Independent newspaper rounded out the nationals with the lowest daily readership of 772,000, but this was up 6% year-on-year.
News of the World remains the highest read Sunday newspaper with 8.22m readers, which is up by 1% year-on-year.