The average issue readership of the Alexander Lebedev-owned Sunday paper was an estimated 469,000 in the year to June, the survey claimed – down from 623,000 the previous year.
The Sunday newspaper market – in which all but The Observer shed readers – saw three other papers suffer big falls: The Sunday Times, The People and the Daily Star Sunday.
The Sunday Times dropped to a readership of 2,794,000 in the period – a year-on-year fall of 11%. However, it remained the most-read quality national newspaper.
The data captures the period of relative calm before the reshaping of the Sunday market brought by the closure of the News of the World in the first half of July.
The News International tabloid was far and away the most-read Sunday newspaper in the year to June, with an estimated 7,353,000 readers looking over each issue – a year-on-year drop of 3%.
By contrast, Trinity Mirror’s The People saw its readership drop 10% year on year to 1,184,000, while the Daily Star Sunday dropped 11% to 860,000 over the same period.
The People’s stablemate, the Sunday Mirror, saw its readership drop by 8% to 3,529,000.
The Mail on Sunday and the Sunday Express each also dropped 3% of their readers over the period, to estimated readerships of 4,866,000 and 1,491,000 respectively.
The Sunday Telegraph recorded a 6% dip in readers as it registered an estimated readership of 1,476,000.
The Observer was the sole Sunday paper to escape a drop. Its readership held steady, remaining flat year on year at 1,140,000, the NRS said.
In the daily market, The Guardian was the only national newspaper to gain readers, rising 1% to 1,143,000.
The readership of two further papers remained flat. The Sun and the Daily Express, respectively, drew readerships of 7,683,000 and 1,457,000. The Sun remained the nation’s most-widely read newspaper.
The Financial Times experienced the biggest fall in estimated readership of the daily papers, dipping 15% to 344,000.
The Independent, The Times and the Daily Record were the other daily papers to suffer double-digit drops – down 12%, 11% and 10% respectively to readerships of 535,000, 1,486,000 and 859,000.
There were dips of 6% for the Daily Star, the Daily Mail and The Daily Telegraph to 1,498,000, 4,622,000 and 1,688,000 respectively.
The Daily Mirror’s readership dropped 2% to 3,163,000 year on year in the 12-month period.
Unlike figures from the Audit Bureau of Circulations, which track sales and distribution performance, the NRS surveys around 36,000 people to produce a national readership estimate.
ABC figures, although not for a directly comparable time period, suggest the opposite experience for the Independent titles and their Guardian Media Group rivals.
For example, the Independent on Sunday's average circulation in the six months to June was down just 4% year on year in 2011, to 152,507 copies, while The Observer was down 11.6% to 298,264 copies.
The Independent was down 3.3% to 180,814 copies and The Guardian was down 9.3% to 263,458 copies.
As ever, the practice of giving away bulk copies for sampling (for which only individual monthly data is available) complicates the picture.
In June 2011 The Independent gave away 73,940 copies, up from 62,447 copies in June 2010. The Guardian did not give away any bulks in either month.