England's top state secondary schools are fast becoming the preserve of the middle classes who can afford to move to good catchment areas, researchers have warned, as thousands of children across the country wait to receive their secondary school places for September.

New research, published on National Offer Day, shows young people from the poorest families are much less likely to win places at the one of the country’s top 500 comprehensive schools for GCSE results.

These secondary schools are significantly more “socially selective” that the average state school, taking around half the population of disadvantaged pupils than the average state school, analysis by the Sutton Trust concludes.

Faith schools were found to be the most socially selective group of top schools – more than three times more selective as non-faith schools - making up a third of the top 500 group.

The social mobility charity has called on the Government to introduce the use of ballots - where a proportion of places is allocated randomly - or banding across abilities to achieve a more balanced intake in each catchment area.

Hundreds of thousands of children across the country expect to receive notice of their allocation secondary school on Wednesday evening, with thousands expected to miss out on their first choice.

While the findings suggest a slight improvement within the past couple of years – the average proportion of poorer pupils placed in the best schools at 9.4 per cent up from 7.6 per cent in 2013 - Government data suggests parents in many areas of England are finding it more difficult to get their child into their preferred secondary school than they were a year ago.

The most expensive schools in the world Show all 10 1 /10 The most expensive schools in the world The most expensive schools in the world La Rosey, Switzerland This prestigious Swiss boarding school is believed to be the most expensive in the world. Le Rosey hosts pupils from seven to 18 and has been co-educational since 1967. The school takes in pupils from more than 60 countries, but allows no more than 10 per cent of its students to come from any one country in order to prevent a single nationality dominating. The school has two campuses – winter is spent in Gstaad, where pupils can make use of the ski slopes after their morning lessons. Come spring, the whole school will uproot to the Chataeau du Rosey in the village of Rolle by Lake Geneva. Le Rosey also boats a 1,000 seat concert hall, equestrian centre and 38-foot yacht. Notable alumni: Shah of Iran, Prince Rainier of Monaco and King Farouk of Egypt. Sir Roger Moore and Elizabeth Taylor also send their children here, along with John Lennon’s son Sean and Winston Churchill’s grandson. Fees: approx. £86,657 pa The most expensive schools in the world Aiglon College, Switzerland With a view of Mont Blanc, this high altitude school lends itself to outdoor pursuits. The school caters for boys and girls aged nine to 18 and is modelled on the traditional British Boarding school. Unlike most schools, however, the whole school body comes together for 20 minutes of meditation on three mornings each week. Notable alumni: Actor Michel Gill, Princess Tatiana of Greece and Denmark, Sheherazade Goldsmith Fees: up to £80,810 per year (upper school boarding) The most expensive schools in the world Collège Alpin International Beau Soleil Founded in 1910, Beau Soleil is one of the oldest private boarding schools in Switzerland. It is positioned 1,350 metres above sea level on the Swiss Alps and hosts pupils from more than 40 different nationalities aged 11-18. The curriculum is taught in both French and English and focuses on outdoor sports, with a ski slope and ice skating rink on site. Notable alumni: Racing driver Jacques Villeneuve, Princess Marie of Denmark, Prince Guillaume, Hereditary Grand Duke of Luxembourg Fees: £79,528 Collège Alpin International Beau Soleil The most expensive schools in the world Collège du Léman International School, Switzerland Taking in children from as young as one year old, College du Leman teaches a bilingual programme of French and English up to age 18. The school campus stretches out across eight hectares and offers access to both Geneva city and the mountains. Pupils from more than 100 nationalities attend. Noteable alumni: Anna Ovcharova, Swiss, Russian figure skater Fees: £68,960 pa The most expensive schools in the world Leysin American School, Switzerland Another high-profile Swiss school, popular for its exclusive ski and snowboard facilities. LAS Students are allowed to spend Tuesday and Thursday afternoons on the mountain for sports. Despite its name, around 12 per cent of students are from the US. Notable alumni: According to Bloomberg, alumni include members of Saudi Arabia’s royal family, the Rockefellers and Vanderbilts. Fees: Approx £66,700 per year Leysin American School The most expensive schools in the world Institut auf dem Rosenberg With just 260 boarding pupils from over 40 countries, emphasis is placed on one-on-one time at the Institut auf dem Rosenberg. The school has a staff to student ratio of 1:4 and average class sizes of 8 students. Pupils can choose fromn one of five curricula, including British A level,s German Abitur and the Swiss Matura program. Notable alumni: Countless politicians and business leaders as well as international royalty – the school operates a strict privacy policy but most studenrts come from entrepreneurial families or are heirs to large businesses. Fees: £66,160 pa The most expensive schools in the world Think Global School The world’s first “travelling high school” takes pupils to four different countries each year – allowing pupils to experience subjects out in the field. The school has one teacher for every three students and has a 100 per cent pass rate for the International Baccalaureate qualification. Notable alumni: The school is only seven years old, but will no doubt become a popular choice with the next generation of rock stars’ children. Fees: £63,980. Sliding-scale scholarships offered. The most expensive schools in the world The American school in Switzerland (TASIS) The first US boarding school to be set up in Europe, TASIS lies on the Dollina d’Oro in the Swiss mountains. Fine art is central to the school curriculum and TASIS hosts its own Spring Arts Festival which attracts a number of famous artists and musicians each year. Notable alumni: American mountain climber Francys Arsentiev, Performer Jeanie Cunningham and Italian-American film director Francesca Gregorini Fees: £63,561 pa The most expensive schools in the world Brillantmont, Switzerland A family-run, traditional Swiss school for 130 years, Brillantmont overlooks Lake Geneva and sits just a five-minute walk away from Lausanne. Brillantmont boasts that 100 per cent of its students continue their studies to higher education. Notable alumni: kept suspiciously on the down-low Fees: £52,010 - £59,680 pa Brillantmont, Switzerland The most expensive schools in the world Hurtwood house, Surrey Hurtwood house, surrey Several of the best UK boarding schools top their fees around this mark. Set in an Edwardian mansion with 200 acres of grounds, Hurtwood House is one of the most unique. The school hosts just 340 pupils and is known for its focus on creativity and the arts – a recent school production of Chicago cost £75,000 to stage, according to Tatler. Notable alumni: Emily Blunt, Jack Huston, Hans Zimmer Fees: £39,555 pa

Since this time last year, more than half of towns and counties have seen a fall in the numbers of 11-year-olds winning a place at their first choice school, with two-thirds of local authorities experiencing a drop overall.

According to the report, top performing schools admit around 9.4 per cent of pupils eligible for Free School Meals (FSM) - a key measure of poverty - compared to 17.2 per cent attending the average state school.

Around half of this gap is down to schools having catchment areas that have lower numbers of disadvantaged pupils, but social selection is also to blame, researchers argue.

Some 85 per cent of the top 500 schools were found to be taking on fewer disadvantaged pupils than they should do, given the numbers living in their catchment area.

The Government has discussed lifting the restrictions on the proportion of pupils new faith schools can select on the basis of religious faith (currently 50 per cent) in a bid to improve social mobility.

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But Sutton Trust researchers warn that lifting the restriction is likely to make faith schools “even more unrepresentative of their local areas, reducing the number of good school places available to pupils across the socio-economic spectrum”.

The study also highlights evidence of a house price premium marked at around 20 per cent attached to living in the right area for a top comprehensive school.

A typical house in one of these catchment areas costs around £45,700 more than the average property in the same local authority.

Many families are paying up to hundreds of thousands of pounds more for their homes in order to get their children into the country's very best state schools, it was revealed last year.

This means that pupils whose families can afford to buy in these coveted areas are more likely to get a place at one of the top secondary schools, effectively pricing poorer families out, experts warn.

Researchers also looked at the Government's new Progress 8 measure - which looks at the progress and achievement of a pupil over eight subjects and found that the schools with the best results on this measure had a higher proportion of FSM children, at 15.2.

Sutton trust chairman Sir Peter Lampl, said: “Getting a place at a high attaining school is key to getting on in life. Yet the bottom line is your chances of doing that depends on your parents' income and whether they can afford the extra £45,700 house premium to live in the catchment area.

”This is why we want to see more use of ballots - where a proportion of places is allocated randomly. Ballots would ensure that a wider mix of pupils would get into the best schools.“

Commenting on the report, Selective Comprehensives 2017, Kevin Courtney, General Secretary of the NUT, said the teaching union disagreed with the idea that a school’s quality could be judged solely by GCSE or Progress 8 scores.

“Most schools work extremely hard to provide pupils with a broad and balanced curriculum that includes a wide, interesting and challenging set of subjects, many of which are not included in these measures,” he said.

He added that the report did raise a number of “disturbing issues”, however, including information that 80 per cent of all secondary schools are now their own admission authorities.

“As the report reveals, there is evidence of covert social selection taking place in many schools,” he said, “with the 500 so-called ‘top performing’ schools having a proportion of children eligible for free school meals that is scarcely more than half the national average.

“This is not a situation that can be allowed to continue. Yet if the Government presses ahead with its stated aim of seeing all schools become academies by 2022, it is one that can only get worse with more schools becoming responsible for their own admission arrangements.

“The only solution is to return the role of admission authority for all schools in a local area to the local authority. That way parents can be assured that the system for admission to school is fair and transparent and not influenced by the social status of their family.”

A Department for Education spokesperson said: “Selection by house price is simply unfair which is why we’ve already set in motion plans to tackle it. We plan to create more good school places in more parts of the country by scrapping the ban on new grammar schools, as well as harnessing the expertise and resources of our universities, and our independent and faith schools.