The former England international won by a margin of 28 votes to 23.

He was standing for re-election against Pichot, who served as his vice-chairman before announcing his intention to challenge Sir Bill for the leadership last month.

The result of the election was not expected to be announced until May 12, when an annual meeting is due to be held online, but World Rugby said yesterday that the winner would instead be revealed two days after voting closed.

"I am honoured to accept the mandate of the World Rugby Council to serve as the international federation’s Chairman once again and would like to thank my union and region colleagues, members of the global rugby family and, of course, my family for their full support and trust," Sir Bill said.

"I would like to thank Gus [Pichot] for his friendship and support over the last four years. 

"While we stood against each other in this campaign, we were aligned in many ways and I have the utmost respect for him. 

"Gus is passionate about the sport and his contribution has been significant."

Pichot had positioned himself as the candidate for change, saying he wanted "global realignment of our game".

However, Sir Bill was known to have loyal backing in the northern hemisphere, with the unions which make up the Six Nations expected to support his bid - accounting for 18 of the 51 available votes.

The Welsh Rugby Union, Rugby Europe and Rugby Canada all said publicly that they had voted for Sir Bill, while New Zealand Rugby and Rugby Australia endorsed Pichot as he was expected to receive unanimous support from the SANZAAR bloc, which also includes his native Argentina and South Africa.

Support from any union in the Six Nations that backed Sir Bill would have been enough to see Pichot elected instead.

Sir Bill ran with Bernard Laporte, President of the French Rugby Federation (FFR), as vice-chairman.

Sir Bill claimed in his manifesto that he wanted to have "a more representative and diverse International Federation that better serves the game, not one that is seen to only support the 'old guard', although was viewed by many as part of that old guard.

"Now is not the time for celebration," Sir Bill said after being re-elected.

"We have work to do. 

"We are tackling COVID-19 and must implement an appropriate return-to-rugby strategy that prioritises player welfare, while optimising any opportunity to return to international rugby this year in full collaboration with club competitions for the good of players, fans and the overall financial health of the sport."

Elections were also held for the Executive Committee, but only seven candidates stood for the seven positions in the end.

Fiji's Ratu Vilikesa Bulewa Francis Kean withdrew his candidacy after allegations of homophobia and discrimination emerged, having had his nomination seconded by the FFR.

The 12-person Executive Committee will now consist of chairman Sir Bill, vice-chairman Laporte, World Rugby chief executive Brett Gosper, independents Angela Ruggiero and Lord Mervyn Davies, Mark Alexander of South African Rugby Union, Rugby Africa President Khaled Babbou, New Zealand Rugby's Bart Campbell, Gareth Davies of the Welsh Rugby Union, John Jeffrey of Scottish Rugby, USA Rugby's Bob Latham and Brett Robinson of Rugby Australia.

The Fiji Rugby Union, for which Kean was chairman before be stood down, had seconded Sir Bill's nomination for re-election.

Sir Bill and Laporte also suggested in their manifesto that they are open to players switching international allegiance, vowing to review eligibility criteria which currently prohibits players from representing a second international union in their careers, which would be a popular move in the Pacific Islands, which suffer from a talent drain.

Fiji and Samoa are among the seven unions given one vote in the election, along with Canada, the United States, Uruguay, Georgia and Romania.

Each of the 10 Tier 1 unions in the Six Nations and Rugby Championship get three votes, while the six regional associations - Africa, Asia, Europe, Oceania, North plus Central America and South America - have two votes, as does Japan.

The election has been handled by PricewaterhouseCoopers, which told the World Rugby Council yesterday that there was a clear winner after the first round of voting, prompting the announcement of the victor to be moved forward.

Pichot tweeted his congratulations to Sir Bill.

"Not this time, thanks to all fo (sic) the support, from the bottom of my heart", Pichot wrote.