When Wolverhampton Wanderers unveiled as their new coach Nuno Espírito Santo, the first client of the globe-bestriding Portuguese agent Jorge Mendes, the club denied that Mendes had garnered an excessive influence in their transfer dealings.

Wolves’ managing director, Laurie Dalrymple, acknowledged that Mendes was a “known associate” and friend of the club’s Chinese owner, but said it would be against football rules for an agent to be in charge of recruitment. Mendes’s role is advisory, he said: “Someone, because of the friendship with the owners, that we take opinions and advice from.”

Mendes’s relationship with the Fosun conglomerate, which bought the club last summer from the house-building magnate Steve Morgan, goes beyond friendship and advice: they have a business partnership and Mendes has been central to Fosun’s moves into football.

He is understood to have helped identify Wolves as a prospect to buy, when like other Chinese investors Fosun followed China’s president Xi Jinping’s call in 2015 for the country to expand its football power at home and overseas. The former Chelsea chief executive Peter Kenyon, who has worked with Mendes for years including in a company buying third-party ownership stakes in players, is understood to have acted for Fosun in negotiating the Wolves takeover.

Nuno confirmed that he was still represented by Mendes, who was a nightclub owner when they met 21 years ago, launching a stellar and lucrative trajectory of football dealmaking by negotiating the then goalkeeper’s move from the Portuguese club Vitória Guimarães to Deportivo La Coruña in Spain.

After Nuno’s playing career ended, his appointments as a coach have all been with clubs where Mendes is very well connected: Portuguese Primeira Liga club Rio Ave, Valencia, where Mendes has been centrally involved with the owner Peter Lim, and Porto, whom Nuno managed to second place in Portugal last season.

Nuno said he and his coaching team had had “nice options” from other clubs but that he had been impressed with Wolves’ facilities and the challenge of managing in England. To questions from local reporters about Mendes’s influence, Nuno responded only: “I am a client of the best agent in the world. I do my job; he does his job.”

Wolves’ second signing for Nuno on 14 June has all the indications of his agent’s influence: Roderick Miranda, a 26-year-old Portuguese defender, came from Rio Ave, where he played for four years, having begun his career with Benfica. The intermediaries who acted on last season’s signings are named in the list of all English club transfers published by the Football Association in April but Wolves declined to state if Mendes was involved in the Miranda signing.

Like other prominent agents, Mendes was quick to make his services available to the huge new flow of Chinese interest and money in football, before Xi reversed the policy last year after China’s clubs paid huge fees to sign players, and Wolves, Birmingham City, West Bromwich Albion and Aston Villa, among other European clubs, had been bought.

Shanghai Foyo, a company majority owned by Fosun’s chairman, Guo Guangchang, bought stakes in Mendes’s agency Gestifute’s holding company, Start. In January 2016 Gestifute and Shanghai Foyo launched a marketing and football agency joint venture in Chinese football with a glitzy event in Shanghai attended by Guo, Mendes and senior figures from Benfica and Monaco, clubs where Mendes has been key to transfers.

Fosun, which owns huge industrial, pharmaceutical and entertainment holdings, then bought Wolves after Morgan became disillusioned with his treatment from a section of supporters and decided to sell. Fosun, owned by Guo and two other shareholders, paid £30m, returning the investment Morgan had made after buying Wolves for £10 from the former owner, Sir Jack Hayward, in 2007. The then chief executive, Jez Moxey, decided not to stay on, partly looking for a change after 16 years but partly, it is understood, because he did not relish the influence Mendes would have with the owners and on recruitment of players.

Morgan and Moxey ran Wolves prudently despite the disappointment of double relegation from the Premier League to League One in 2012 and 2013. The club bought land for development around Molineux, invested in the stadium, training ground and facilities, were promoted back to the Championship in 2014, and made a £6m profit last year.

The Portugal midfielder Ivan Cavaleiro, left, was bought by Wolves from Monaco in a deal in which Jorge Mendes’s influence was clearly evident. Photograph: Seconds Left/Rex/Shutterstock

Fosun, owning Wolves via a British Virgin Islands-registered holding company, paid in a loan of £21m immediately on taking over, and £17m was spent on players.

Mendes’s influence was clearly evident in some of those signings, including Wolves paying a club transfer record, £7m to Monaco, for the Portugal midfielder Ivan Cavaleiro.

In the list of signings now published annually by the FA, the “intermediaries” involved in that deal are stated to have been Carlos Osório de Castro, a lawyer based in Portugal who acted for Cavaleiro, and Valdir Cardoso, a Portuguese agent understood to work for Gestifute, which represented the club.

Wolves then exceeded that record fee in January, paying £13m for the Portuguese midfield player Helder Costa, also to Monaco, who had loaned him to Molineux in July after the Fosun takeover. The FA document shows that the same two intermediaries acted: Carlos Osório de Castro for Costa, Cardoso for Wolves.

Carlos Osório de Castro is said to have acted as Gestifute’s lawyer for many years; he responded to an email from the Guardian by saying “It’s my firm’s policy not to comment on any issue regarding the work we perform [or are alleged to have performed] for our clients. I’d just like to point out that my firm represents a lot of players not connected to Gestifute, along with several clubs and football federations and investors.”

When another Portuguese player, João Teixeira, joined Wolves on loan from Benfica, the FA’s list of transactions states that he did not have any agent advising him at all, while Andy Quinn, a director of Gestifute International based in Ireland, acted for Wolves. The Portuguese defender Silvio, who signed from Atlético Madrid in July, is not listed in the FA document so the agents on that deal have not been publicly disclosed.

Of 12 players signed rapidly after the takeover, only Costa was an unqualified success, and Wolves finished 15th in the Championship. Paul Lambert, the second full-time manager employed by Fosun last season, left despite the club’s main director, Jeff Shi, having expressed “trust and confidence” in him weeks earlier.

Lambert was reported to be unhappy with the influence of Mendes over player recruitment; Dalrymple, however, said last week that the owners’ attitude to Lambert changed when the team failed to “kick on” through April.

In response to questions about the relationship with Mendes, Wolves said they did not comment on “specific financial matters” or individual agents’ fees. In fact, the money Wolves paid to intermediaries last season, £1.25m, was less than most large Championship clubs

In a statement, Wolves said: “It is a matter of public record that Fosun have a percentage stake in the Gestifute company headed up by Jorge Mendes. Jorge is available as an adviser to the owners, in the same way as many other agents and influential figures within football are. Wolves have signed players within his portfolio, including last year’s player of the season Helder Costa, as well as players from other intermediaries.

“However, the owners continue to lead on all key decisions, working closely with the board of directors and Wolves’ recruitment team, and taking into account any advice that they receive.”

Gestifute did not respond to questions. Jorge Mendes will expect to be busy this summer.

Additional reporting on financial and company information in China by the writer Alvin Ho