By Katherine Sellgren
BBC News education and family reporter
Do the league tables alter the view on London's schooling?
London is the highest performing region in England at GCSE level, the latest secondary school league tables show.
The data shows 54% of pupils achieved the benchmark of five GCSEs at A* to C, including English and maths, in 2009.
This is a striking turn-around in just over a decade - in 1997, just 29.9% of London's pupils reached this level.
Apart from the South East, London is the only region which has already met the government's 2011 target of 53% of pupils attaining the GCSE benchmark.
Indeed, London's state school pupils have outperformed the national average in GCSE performance every year since 2005.
In 2009, they were well ahead of the national average (50.7%) of pupils getting five A* to Cs, including maths and English.
And of the 247 secondary schools in England which are failing to get over 30% of pupils reaching the GCSE benchmark, just 13 are in London.
The improvements could be put down in part to the London Challenge - now rolled out across England as the National Challenge - which was launched in 2003.
PUPILS MEETING GCSE BENCHMARK BY REGION
South East 53.7%
East of England 51.9%
South West 51.8%
East Midlands 49.9%
North West 49.9%
West Midlands 48.5%
North East 48.1%
Yorkshire and Humber 47.3%
The school improvement programme offers extra support to struggling schools, particularly in maths and English, and to low-performing boroughs.
But, while the government would put the improved London performance down to this improvement scheme, it could also be a question of demographics.
Tony Travers, director of the Greater London Group at the London School of Economics, says much of the success of London schools in recent years can be explained by high levels of immigration in the capital.
"Migrants tend to be aspirational and hardworking and their children are often driven to do well in the country in which they arrive," he says.
"Migrants have often made an extraordinary effort to move here and are likely to be people who wish and expect to do well, so it would be surprising if their children didn't do well.
"Vietnamese, Chinese and Indian children, to name but three groups, tend to do extremely well in exams."
There is also the impact of middle class families either opting or being forced to stay in the capital.
Mr Travers says there is recent evidence of an "enormous slowdown" in property selling and buying, particularly with the recession biting.
London is a city of changing demographics
"So if the affluent middle-classes have traditionally moved out - to Buckinghamshire, Hertfordshire, Essex - around the time their children start secondary school, then there is some slowdown in that moving out process," he says.
A study published by the University and College Union in October suggests London has become a magnet for graduate workers, who may be more likely to encourage their children to do well at school.
The UCU research found that 17 of the 25 constituencies in England, Scotland and Wales with the highest numbers of graduates were in London.
For example, in Hackney North and Stoke Newington and in Ealing, Acton and Shepherd's Bush, 50% of the population has a degree, making these two constituencies better educated than more affluent areas such as Winchester and Bath.
But whatever the reasons for the improved attainment, the league table data paints a comforting picture for families in London.
Of the 10 most improved local authorities for GCSE performance from 1998 to 2009, nine were London boroughs.
At the top of the tree, Kensington and Chelsea has improved by 36.6 percentage points since 1998, Hackney by 35.3 percentage points and Lambeth by 33.8.
And of the 10 most improved local authorities in the past year, Hackney was top with a 9.6 percentage points improvement on 2008 in 2009.
Hammersmith and Fulham was the third most improved local education authority on 2008, with an 8.5 percentage points improvement.