As Mark Sampson took his seat in a quiet corner of a hotel restaurant someone gestured to the small group of journalists gathered at the table and offered him a cycling helmet. “Not yet,” joked the coach of England Women. “Save it for when I really need it.”

Just over two years have passed since that balmy June afternoon in the eastern Canadian city of Moncton, where Sampson and his Lionesses were preparing to begin a watershed World Cup campaign. It concluded with an expectation-exceeding bronze medal, which came gift-wrapped in a series of eulogies to an engaging young Welshman possessing coaching ability, tactical acumen, managerial skills and – for the coach of a senior England side –refreshing candour.

Another semi-final appearance at this summer’s Euro 2017 – this time a defeat by the hosts, Holland – has had a starkly different aftermath. Less than two months after being warmly applauded by reporters in Enschede, the 34-year-old is the unhappy focus of bullying and racism allegations from two of his former players. As he prepares his team for Tuesday night’s World Cup qualifier against Russia at Tranmere Rovers’ Prenton Park, Sampson’s career and reputation are threatened by a controversy which could also have serious repercussions in the Football Association’s corridors of power.

In August it emerged that Eni Aluko – a forward of Nigerian heritage with 102 caps – had been paid around £80,000 by the Football Association in the lead-up to the Euros after detailing a series of concerns about Sampson’s treatment of herself and of her Chelsea team-mate Drew Spence, a mixed-race midfielder and the holder of two England caps. Aluko, who has scored 33 times for the national team, had not been called up since May last year.

An FA internal review exonerated the England coach and that was followed up by an independent inquiry, paid for the by the governing body and conducted by the barrister Katharine Newton. It found no evidence to support any of the striker’s claims. Sampson himself strenuously denied any wrongdoing.

The crisis deepened when Aluko alleged that before a fixture at Wembley in 2014 Sampson had told her to ensure her Nigerian family did not bring the Ebola virus to the game. He denies making what the Professional Footballers’ Association has described as a racist joke and, despite Sampson having since appeared to contradict his own evidence, his employers at the FA are standing by their coach.

The FA had appeared determined to resist calls for a third inquiry but the governing body is now reopening the independent inquiry under Newton after Spence finally came forward this past week to tell the governing body she had been left “upset and offended” by Sampson’s asking her how many times she had been arrested during a midfielders’ meeting at the 2015 China Cup. Again England’s manager denies making those comments.

With key questions unanswered, FA officials have now been summoned to parliament to face the House of Commons culture, media and sport select committee next month, when they will be asked to explain the processes involved in their two investigations to date.

More immediately Sampson must prepare for Tuesday’s qualifier. In assorted interviews he has denied all complaints against him, stating: “My conscience is clear.” Unsurprisingly a coach noted for his ready stream of jokes seems to have lost his sense of humour, instead talking of “the pressure” he and his family are under.

His FA bosses at both Wembley and St George’s Park are confident Sampson retains the full support of the players who contested Euro 2017. Little did the squad know, during their time in the Netherlands at a tournament England should arguably have won, that he was privately braced for the emergence of Aluko’s allegations.

The resultant stress perhaps throws some light on his comments about Olivier Echouafni, his France counterpart, being “wet behind the ears”, that Spain were adept at practising “dark arts” and his belief in “standing up for myself” and “fighting back” if someone should “poke me in the eye”.

At the time it was easy to miss this subtext. On the surface little appeared to have changed since Canada. Back in 2015 a Lionesses camp that had become jaded and semi-mutinous towards the end of his predecessor Hope Powell’s more authoritarian tenure seemed to enjoy the freedoms introduced by Sampson. He worked his squad hard but allowed them to venture out of the England hotel unsupervised, treating his players as adults who were allowed to talk to the press and debate tactics unfettered by FA minders tape-recording every conversation.

Various Lionesses praised their coach, appearing to accept his team rotation, use of psychology and emphasis on team bonding. An air of harmony, openness and, above all, meritocracy prevailed.

Along the road to a third-place play-off win against Germany in Canada, a coach mentored by Roberto Martínez during a stint in charge of Swansea City’s academy – where he helped develop Stoke’s Joe Allen and Tottenham’s Ben Davies – made some bold decisions. They included an unexpected switch to a back three in that play-off in Edmonton and the earlier decision to fast-track Jodie Taylor back from knee surgery in the hope his best finisher would be fit enough to lead the attack in the quarter-final against the hosts.

Mark Sampson is shrugged off by Lucy Bronze in an England training session. Photograph: Mike Egerton/PA

Sampson clearly felt that, although Aluko was prolific at club level and in qualifying games, she seemed to struggle at World Cups, having failed to score in nine appearances over three tournaments. So when the medical staff cleared a barely fit Taylor to start in front of a 54,000 crowd in Vancouver, Sampson picked her and left Aluko on the bench. When Taylor, the winner of Euro 2017’s Golden Boot, scored in England’s 2-1 victory, the coach’s gamble seemed vindicated.

More recently he controversially ignored Beth Mead’s claims to an England place after the then Sunderland striker finished as the leading scorer in the 2015 Women’s Super League. An impressive win ratio meant that few challenged his footballing judgment. England Women now sit third in the Fifa rankings, behind the USA and Germany, having risen from 15th.

The England men’s senior manager, Gareth Southgate, has described the sports development graduate as an “excellent character” and Sampson seemed very much at the vanguard of the new-school St George’s Park coaching culture. Within the Lionesses’ camp key players have shown loyalty to their coach despite the allegations of racism and bullying. Last week Steph Houghton, England’s captain, said: “Of course I back Mark. We’re all together behind him. Mark has allowed us to be open, to be individual, to really be ourselves and be the best players and people we can be. Since Mark’s been in charge I’ve really enjoyed every moment in this environment.”

Nonetheless Aluko sees things very differently. She alleges Sampson told her she was being dropped for “unLioness” behaviour and that, when pressed for details, “the best he could come up with was that I had looked withdrawn in meetings”. The Chelsea striker has been supported by Lianne Sanderson and Anita Asante, former England players also dropped by Sampson. Of the current England culture Sanderson says: “Everyone must conform.” Clearly troubling divisions exist at the elite level of the England women’s game.

Unlike some of the new breed of football technocrats Sampson landed his big break under Martínez the hard way. Back in that Moncton restaurant he told us about his father, Derek, who, along with his mother, sister, brother and girlfriend, followed the Lionesses around Canada. “He’s my biggest judge,” he said. “You guys think you’re tough but wait until you meet him. It’s not easy to get a ‘well done’ out of him. I was devastated when, at 16, Dad told me I wasn’t good enough to play football professionally but he was right and I quickly became a coach. I was here, there and everywhere, dawn to dusk. I worked with under-fives, right through to senior level.”

With coaching barely covering his expenses, Sampson worked shifts at Cardiff’s Royal Mail sorting office. Raised in Creigiau, a district of the Welsh capital, he attended university in the city and before leaving Swansea juggled life as a semi-pro defender with coaching Taffs Well. “Although Mark was probably paid only his petrol money he was so professional,” says Liam Edwards, the Taffs Well chairman, who paints the picture of an enlightened coach. “Mark’s coaching was exceptional but so was his man-management. He never raised his voice, he didn’t believe in shouting at players.”

After Taffs Well five successful years with Bristol Academy’s women caught admiring FA eyes and in December 2013 he replaced Powell, the decision to hire a male coach drawing disapproval from the anti-discrimination campaigner Lord Ouseley. The chairman of Kick It Out called the appointment of Sampson “an insult to women”. But the FA has stood by the decision, its director of women’s football, Kelly Simmons, saying: “It was about appointing the best person for the job and the recruitment process was open to all.”

Before leaving the Netherlands last month Sampson urged the media to help maintain interest in women’s football. “It would be great to see you all at the Russia game,” he said, looking ahead to the match at Prenton Park.

He is likely to be granted his wish on Tuesday but with the scrutiny on his tenure as Lionesses coach growing by the day, it is the man in the dugout rather than the players on the pitch who will be the focus of attention.

TIMELINE: HOW THE PRESSURE ON THE ENGLAND WOMEN’S COACH HAS INTENSIFIED

7 Aug It emerges Eni Aluko, the England Women and Chelsea forward, made claims of bullying and harassment against Mark Sampson and his staff in May 2016. A Football Association investigation concluded in March 2017 has cleared Sampson and his staff of wrongdoing but it emerges Aluko was paid a settlement in a confidentiality agreement, which the FA insisted was to avoid disruption to England’s Euro 2017 campaign in the Netherlands, where the Lionesses reached the semi-finals.

16 Aug Details become public of an allegation made by Aluko, claiming Sampson made a remark towards another player with ”racial and prejudicial connotations”. Sampson is alleged to have made reference to the number of times a player had been arrested.

17Aug As pressure grows for more details to be released, the FA puts out a statement from Sampson saying he welcomed the investigation and would be looking to improve his communication skills.

21 Aug Aluko (pictured right) speaks publicly on the matter for the first time and alleges Sampson made a racist comment to her before an England game. After telling Sampson she had relatives coming from Nigeria to watch the international, Aluko claims Sampson replied: “Well make sure they don’t come over with Ebola.”

22 Aug The Professional Footballers’ Association backs calls for a new investigation into how Aluko’s complaints were handled by the FA.

5 Sept Sampson speaks publicly for the first time about the allegations and says his conscience is clear.

11 Sept Damian Collins, chair of the House of Commons culture, media and sport select committee, tells the Guardian the committee is very concerned about the matter and will summon senior executives from the FA to answer questions.

12 Sept Sampson appears to contradict evidence he gave to the inquiry when he tells a press conference he cannot recall ever having a conversation about Ebola with Aluko.

14 Sept The Guardian reveals the Football Association is giving serious consideration to launching a new investigation into the Sampson affair after Drew Spence, one of the two players to allege he had made a racial remark, comes forward for the first time to tell the governing body that what Aluko has said about the England women’s team manager is true.

16 Sept Another Guardian exclusive reveals the FAhas been shown potentially crucial text messages that will form part of the evidence against Sampson. The contemporaneous texts from the China Cup tournament are of the players discussing what they heard said about Spence.