19 December, 1992. Barcelona.

It is nearly 6.45pm on a cold, grey evening at Espanyol's Sarría stadium. Los Pericos are hosting third-bottom Albacete and are winning 1-0. Eight-year-old Andrés Iniesta, a passionate Albacete supporter, is glued to his radio back home in Fuentealbilla, praying for an equaliser. This is his team's second season in La Primera and he fears relegation. They are fighting tooth and nail when it all clicks for Espanyol and they produce 40 seconds of world-class football.

Playing out from the back, they weave together four successive one-twos and Goyo Fonseca finishes with elegance. In that instant a small, dapper, bespectacled man leaps off the bench to acknowledge the exceptional football he's just witnessed.

Remarkably, it is Ginés Meléndez, Albacete's coach that day, celebrating the goal conceded by his team. Albacete are now 2-0 down with two minutes left and the result will leave them in the bottom three over Christmas, but this is a guy who lives for excellence, not expediency.

After the match, he says: "We were producing a really good second half and just when we were most dominant, Espanyol put us away with a move which was the best I've seen from any team this season. I got up to applaud them because if you are a good sportsman, if you love football, then you simply have to recognise the quality."

Flash forward 18 years and everyone is desperately looking for Meléndez.

Andrés Iniesta celebrates scoring in the 2010 World Cup final. Photograph: Jerry Lampen/Reuters

When Iniesta scores the goal that wins the 2010 World Cup in Soccer City stadium, every media outlet in Spain wants to know: is this the apogee, or will we be able to sustain success?

Iniesta had progressed through the youth set-up designed by Meléndez at Albacete before transferring to FC Barcelona's La Masía academy. By the time of that historic goal in South Africa, Meléndez had been in charge of youth development (categorías inferiores) at the Spanish Football Federation for 10 years. There was only one man to ask.

When we meet at Las Rozas, the national training complex, Meléndez recalls: "They all rushed to me asking, 'How on earth can we keep performing at this level?' and I simply said, 'Don't worry, we have all the reinforcements ready and waiting in the wings'."

It was July 2010 and Spain had just finished runners-up to England in the Uefa Under-17 European Championships. In the three years since Meléndez's brave projection, Spain have won two Uefa Under-19 Championships, two Under-21 Championships and the 2012 European Championship in Poland/Ukraine. He wasn't joking.

Spanish players after winning Euro 2012. Photograph: Jeff Pachoud/AFP/Getty Images

When Spain lined up to face Italy in the final of Euro 2012 they looked like this: Casillas; Arbeloa, Piqué, Ramos, Alba; Xavi, Busquets, Alonso; Silva, Fábregas, Iniesta. Those 11 players had amassed a remarkable 332 youth appearances for Spain. David Silva, the first scorer against Italy, led the group with 54 caps; Fábregas, who provided the assist, 38. The lowest totals were Busquets (3), Arbeloa (7) and Alonso (10).

Spain's record in youth tournaments provides irrefutable proof that the system is in place long before the players get to the senior squad. Since 2001 Spain has won the Under-19 trophy six times (runners-up once); they have been Under-17 champions three times (and runners-up three times); they have won the Under-21 European Championships twice consecutively; they have finished runners-up in the Under-20 World Cup; have twice been runners-up in the Under-17 World Cup and, of course, won the Euro 2008, World Cup 2010 and Euro 2012 tournaments. There has never, in the history of organised football, been such an era of complete dominance.

For Spanish football development the magic number is 55. Every summer, culminating in July, Meléndez, his staff and the 19 regional scouts who work for him on a voluntary basis will meet and agree a list of the best 55 of the 14- and 15-year-olds in the country – five for each position in the Under-15 team.

This process is duplicated for the Under-16s, Under-17s and Under-18s and while the Under-19s and Under-21s will only gather an initial squad of between 33 and 40 players, the process of selecting Spain's senior squad each season will start with Vicente del Bosque and his own staff picking what they consider to be the best 55 national team players.

Gradually those numbers will be whittled down, but it's what happens to the 14- and 15-year-olds which explains one of the unique elements of Spain's development and domination over the last decade.

In December 2012, I was invited to the Spanish Football Federation's (RFEF) Christmas celebrations. The RFEF did me the honour of putting me at a table with Meléndez plus Spain's chief scout and analyst Antolín Gonzalo Martín, Antonio Limones, the executive who handles Spain's travel and accommodation, Javier Miñano, their Judo black belt fitness coach, and Del Bosque's assistant Toni Grande.

During the speeches from the president, Ángel Maria Villar, and Del Bosque, Iniesta's name cropped up. "He's one of my lads," Meléndez told me in a theatrical aside.

This fascinated me. Iniesta hit the FC Barcelona training system aged only 12 – surely the credit for his development was tripartite – his own, his parents and his club? Equally, over the previous few years I'd heard that the Spanish federation had instigated a system which inculcated personal values, training values, playing values and attempted to turn out homogenised international footballers in a manner which was similar to the acclaimed system at FC Barcelona. Given that the national teams, at all age groups, gathered together a few times each year, training for a couple of days and playing a match or a tournament, I couldn't understand how such a concept was feasible.

I went back to Meléndez to follow up our chat.

"In Spain we are almost further ahead than the clubs when it comes to spotting the cream of youth talent. There are tournaments where the best teams in the 19 regions compete at Under-12, Under-16, Under-18 and so on. The 2013 Under-12 national tournament took place a couple of weeks ago in Logroño and we have already selected 24 youngsters from that. Those same boys will be in the Spain Under-15 side in three years. "The key research work is done by 57 scouts, nationwide, who work for us voluntarily. They are elected by their regional federations [Andalucía, Catalonia, Asturias, Basque Country and so on]. We all meet up, once a year, in December and I explain to them precisely what I´m looking for. Then they call me, weekly, with information which is input to a database which I set up when I arrived in 2001."

An example: Teodoro Nieto spotted Xavi and decided to put him in the magic 55 during a regional competition where he was representing Catalonia in Tenerife, not when he was playing for Barça.

Xavi hugs Gaizka Mendieta at the 2002 World Cup. Photograph: Amy Sancetta/AP

In July, the long list of 55 is finalised and the clubs are informed that their star pupils will be requisitioned as of September and – miracle of miracles – the clubs are obliged to hand them over. The big group is split into two. Each group will alternately leave their club for three consecutive days each month, between September and January, to live and practise at Laz Rozas, just outside Madrid. There they will train, take school lessons and have a code of conduct drummed into them.

Meléndez:

"I compiled a list of 10 rules which are presented to the lads in book form. They focus on things like punctuality, respect, friendship. The dressing room has to be left in perfect condition. Hotel rooms should be treated with respect. The boys have to show respect to the kit man, the masseur, their opponents, and the referee. "The rules are important and we always enforce them. On one occasion I sent two lads home just for chatting in the corridor when they should have been resting in their rooms. They all learn here, sometimes the hard way, but they all learn."

By January the group will be culled from 55 to 33, three players per position, and they will keep attending, three days per month until the summer when there will almost always be a tournament.

This, as the national co-ordinator explained to me, is how it functions. "From the minute the boys arrive, aged 15, right up until they're 21, we work with them in exactly the same way, using the same training exercises, so that by the time they have worked their way up through the ranks the players have a perfect grasp of the Spanish game.

"All the players at the World Cup had come through the same system and almost every single one of them had won trophies with Spain at youth level." One of the principal architects of this golden era concurs.

Xavi:

"My first experience of the national side was at a training camp when I was 16. I had to go down to Madrid and work with the other boys including Fernando Llorente, Iker Casillas, Daniel Aranzubia, Pablo Orbaiz. We all felt that those three days would set the course for the rest of our lives. I kept saying to myself, 'It's now or never. I'm either going to leave here a footballer or I'm not'. And as it turned out, I did. "There tends to be much more socialising, more talking at youth level. I made some great friends and I remember a lot of card games. I also remember Iker always producing the winning hand. From under the table, obviously."

The system works and within it, durable friendships blossom which break down both club and geographical barriers. Ideas such as mutual support and respect, and debt to one's parents are the motors of the La Roja machine.

Fernando Torres at Las Rozas in 2004. Photograph: Javier Soriano/AFP/Getty Images

Fernando Torres scored the only goal in the finals of both the Under-16 Championship in 2001 and the Under-19 Championship in 2002. His evaluation of his categorías inferiores reveals the importance placed on unity.

Torres:

"When I was playing in Spain's youth teams it all felt a bit like being in a movie. In the early days I didn't know a soul, but I'd seen a few of the other guys on television and I'd think to myself: 'What the hell am I doing here?' Then gradually I made friends. We'd exchange phone numbers and chat on the phone a couple of times before meeting up at the next Spain camp. That's how the friendships developed. In those days winning was actually less important than the experience of travelling abroad for competitions."

This kind of spirit is not exclusive to Spain, but it´s a cutting-edge part of their success and, certainly, in the UK it is not the norm. Gerard Piqué won the Under-19 Championships in Poland four years before he won the World Cup.

Piqué:

"Much, perhaps all, of the current Spain success is down to our football upbringing. We were always taught: 'Win!' but also that it wasn't simply about winning, more about how you won. The way you went about it on and off the pitch. "Compared to other nations? I'm not sure whether it's a [Spanish] cultural thing or it's something special to this big generation of talent we have right now, but I know the effect that winning together, repeatedly, has had on us. I won with Cesc and Mata, Iker with Xavi and Marchena, Fernando with Iniesta. Eventually, when you unite all that winning experience you magnify what you´ve got and the whole is even greater than the sum of the parts. "I've met so many guys with talent during my youth career – guys in the categorías inferiores for Barça who looked like young candidates to win the Ballon d'Or. But they don't dedicate, they don't follow the rules we are taught. If you have that elite talent, and the football upbringing, and the massive work ethic plus a good feeling amongst your squad mates then you are brothers. Then you can achieve absolutely anything."

• Spain: the inside story of La Roja's historic treble, by Graham Hunter, is out now in hardback and ebook.