It is 10 years since Jamie Oliver began a campaign to improve the quality of food on offer in English schools.

The infamous Turkey Twizzler – a highly processed snack that became the symbol of the celebrity chef’s efforts to wean schools off junk food – was an earlier casualty of Jamie’s School Dinners, pulled from the shelves by maker Bernard Matthews in 2005.

But did Oliver really achieve a school meals revolution?

How much do we spend on school food?

In response to Jamie’s School Dinners, the last government announced a new grant of £240m to help schools increase school lunch take-up between 2008 and 2011.

The money was ring-fenced to cover ingredients, staffing and other costs associated with making meals healthier. From 2011, the grant was included in a bigger pot of money, the dedicated schools grant, and is no longer ring-fenced.

But from September this year, the government has pledged to provide a free hot meal for every child in reception and years 1 and 2 in English state schools.

The amount local authorities were prepared to spend on ingredients was an early battle-line.

Oliver filmed at Kidbrooke School in south east London and found that the average spend for the ingredients of a meal in the school canteen was just 37p per pupil. This led the chef to call for councils to spend at least 50p on food – “half a quid a kid”.

Statistics from the leading charity, the Children’s Food Trust, show the national average ingredients spend was already 52p per meal for primary schools and 67p for secondaries in 2004/05.

There has actually been little increase in money spent on ingredients since then.

In 2011/12, the latest year we know about, primary schools were spending 67p per meal and secondaries 89p. Allow for inflation and that is an increase of about 4p and 7p respectively over seven years.

Over the last four years spending on ingredients has fallen slightly in real terms.

Of course it’s possible that local authorities are getting more for their money, so this doesn’t necessarily mean there has been a fall in the quality of meals.

Are school meals healthier now?

Almost certainly. The last government brought in stack of regulations in 2007: two portions of fruit or veg a day; no more than two portions of deep-fried food a week; no sweets or extra salt.

These rules still stand, although the current government has just done a consultation on simplifying them after getting Henry Dimbleby and John Vincent, co-founders of the Leon restaurant chain, to come up with new draft guidelines.

Not all schools have to abide by the healthy eating rules. Free schools and academies are currently exempt from implementing them, and their numbers are growing.

Are more children eating school dinners?

Of course, all these improvements count for little unless children are actually eating the healthier food on offer now.

And it’s actually difficult to say whether there has been a long-term increase in the take-up of school meals.

Children’s Food Trust statistics show an increase over the last three years we know about, but a change in how the figures were compiled make it impossible to compare this trend with previous years.

Before the previous data set was discontinued, it looked as though the take-up of school dinners actually fell after Jamie Oliver’s series was aired in 2005.

Have children’s diets improved?

Most statistics show the prevalence of obese and overweight children rising in the 1990s and early 2000s, with a flattening or slight downward trend since about 2004.

It remains the case that more than a quarter (28 per cent) of girls and boys aged two to 15 were classed as overweight or obese in the latest Health Survey for England, and public health bodies are united in prioritising childhood obesity as a serious problem.

Of course we don’t know whether changes to the rules in school dinners are responsible for any of these trends.

There remain serious concerns over the quality of the average English child’s diet. The latest National Diet and Nutrition Survey found that 11 per cent of boys and only 8 per cent of girls aged 11 to 18 were eating five portions of fruit and veg a day.

Children were exceeding the guidelines for sugar intake 20 per cent were deficient in vitamin D.