Initial figures released by the NRS showed a 46% increase in the number of London residents taking the survey now compared with 2005.
However, actual numbers reveal there has been no increase since 2007, when questions over NRS' coverage of London intensified when it was London Lite and thelondonpaper.
It was criticised by News International, which said it was "a joke" that NRS interviewers only spoke to 15 readers of thelondonpaper in January 2007.
In 2006 NRS acted to address concerns over participation from Londoners by offering them £25 store vouchers to complete the survey.
The London sample size in the year to September 2009 was 4,126, compared with 4,133 in the same period in 2007 and 2,832 in the same period in 2005.
There has been an increase in the number of men recruited over the period; the number climbed from 1,189 in 2005, to 1,765 in 2007 and to 1,899 in 2009.
In September this year Dan Wood, MediaCom's associate director of press investment, , it needed to do more to accurately measure urban audiences.
Mike Ironside, chief executive of NRS, says: "With eight million residents, London is a key market for publishers of newspapers and magazines.
"It is crucial that a representative sample of people from the capital answer the NRS survey in full, and our figures show we have been able to make this work to greater effect in recent times."
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