The Congress theme was "Sport for a World of Peace". 

“This Congress will help to create a sort of rostrum where participants will be able to express their views concerning the future of sport and the Olympic Movement, their problems and their hopes, in the presence of all the competent organisations," International Olympic Committee (IOC) officials had promised. 

"It is therefore, for the moment, a question of taking stock of the present situation," 

But organisers came in for sharp criticism from journalists, other observers and delegates who accused the IOC of being out of touch.

“If the International Olympic Committee wants to preserve the Olympic Games into the next century it must stop living in the last one," an editorial in Sportsworld magazine said.

The meetings ended with new IOC President Lord Killanin rebuking the Japanese Olympic Committee.(JOC) for trying to apply political pressure in a proposal relating to the admission of Communist China.

In the late 19th and early 20th centuries, Baron Pierre de Coubertin, driving force of the modern Olympic Movement, established Olympic Congresses as regular events alongside annual IOC Sessions.

Even so, there had not been an IOC Congress since 1930 in Berlin.

The 1973 event in Varna had been announced in Mexico City during the 1968 Olympics.

Arrangements were confirmed when the IOC met in Munich shortly before the 1972 Games.

At the time, the IOC still had an entirely male membership.

"This exclusive self electing body must rid itself of the image of a Victorian club membership which depends on being a chap of good breeding who won’t frighten the horses," Sportsworld continued.

Killanin, an Irish peer and Old Etonian, was perhaps the kind of individual that the writers had in mind.

Yet he was seen as a more progressive than his predecessor, octogenarian Avery Brundage, an American multi-millionaire who had become an increasingly polarising figure with his unbending stance on amateurism.

"Under the enlightened chairmanship of Lord Killanin, the Olympic Congress will certainly succeed in living up to the expectations of all those taking part in it and in ensuring that the eternal flame of Olympia continues to burn bright and high," claimed the IOC bulletin.

Killanin had set up a Tripartite Commission to organise the meetings.

Comte Jean de Beaumont of France and Jonkheer Van Karnebeek of The Netherlands represented the IOC, from the International Federations there was FIFA President Sir Stanley Rous, rowing's Thomi Keller and Lieutenant Colonel Rudyard Russell of the International Amateur Boxing Association.

The  National Olympic Committees (NOCs) were represented by Italy’s Giulio Onesti, Konstantin Adrianov of the Soviet Union and Henry Adefope of Nigeria.

General Vladimir Stoytchev, already 81-years-old, was part of the group on behalf of the Bulgarian Olympic Committee.

The themes to be discussed included the redefinition of the Olympic Movement and its future, relations between the IOC, the International Federations and NOCs and plans for future Olympic Games. 

Debates were designed to be part of a consultation process and the Congress regulations insisted that they would "not be sanctioned by votes."

International sports Federations and other organisations had begun to flex their muscles in reaction to what they viewed as over restrictive regulations.

Keller had been agitating for the International Federations to have more power, even at the expense of the IOC.

"The IOC must ally themselves with modern competitive sport and be ready to face the consequences," Keller told the meetings.

"Everybody interested in sport knows that entries for the Olympic Games have largely become an open exhibition of lying which is quite incompatible with the ethics of sport and the spirit of Baron de Coubertin."

It was an opinion with which many agreed.

The 1972 Olympics had attracted over 7,000 to the Games, an unprecedented number.

Prince Philip, President of the International Equestrian Federation and a man known for forthright opinions, made his own contribution to the debates. 

"In my opinion,the IOC should be looking for ways to allow more sports and more competitors to take part in the Olympic Games, not less," Prince Philip said.

"More and more people are taking part in more and more sports, standards are going up and the pressure to take part in international competition is increasing,I would urge the IOC to consider every possible solution to the problems of size even if this means departing from the strictly traditional pattern,"

The Prince had previously made some radical comments but revealed, "When I tried them out on a a member of the IOC, he nearly had an apoplectic fit."

He did not disclose the identity of the member.

Canadian Olympic Association secretary Richard Pound, later to become a highly respected and influential IOC member, was also amongst the speakers. 

"It is our view that any redefinition of the Olympic Movement will not be complete without a critical examination of the eligibility rules," Pound told delegates.

"We are aware that this is an area of concern for almost everyone in the Olympic community."

The Marquess of Exeter, the 1928 Olympic 400 metres hurdles champion and an IOC member since 1933, offered words of caution. 

"Let us think carefully before making any change, the problems faced by the Movement were only caused by its success, why change anything when there was such a triumph?" he asked.

The speech was applauded by a number of IOC members but it was criticised by many for being insular and complacent.

Chris Brasher, Olympic steeplechase gold medallist in 1956, wrote a damning article for The Observer.

"If, at the end of the week, you have been seen to apply sticking plaster to an injury which requires major surgery, you will have been seen to have killed by negligence the most important movement in world sport," Brasher declared.

The question of the two Chinas was destined to be a major diplomatic Olympic issue during the 1970s.

There had been bitter exchanges in the 1950s and Communist China was still excluded from the Olympic Movement as the IOC recognised Nationalist China on the offshore island of Formosa, led by Chiang Kai‐shek.

"Both are insisting that China is one, we have to find a way to put this reality into practice in the world of sport by giving this seat to the People's Republic of China who really represent China in every sense," JOC member Kashuzige Hirasawa said.

Thang Sou-Chiu of Taiwan responded angrily.

"Such behaviour cannot prevail in the end, if we allow politics to interfere in the running of sport, god forbid," he said.

There was also a sharp rebuke from Killanin.

"I personally do not think it is the task of one Olympic Committee to take it upon itself to write around the world asking to recommend suspension of another Olympic Committee however well intentioned that may be," Killanin added.

"We all want China, but it must come in under the proper rules, if there are problems we must discuss them around a table and not by pressure."

Many were critical of the politicised speeches made by delegates from the Communist bloc.

"We are legitimately proud that the USSR and the other Socialist states persistently carry on efforts to strengthen world peace and the principles of peaceful co-existence," Soviet Olympic Committee member Sergei Pavlov said.

The Congress had been opened by the Bulgaria's hard line leader Todor Zhivkov.

"We consider the decision to hold the IOC session in Varna a great honour and a recognition of Bulgarian sport and our Olympic Movement," he said.

When the meeting was over, a final statement claimed, "The speeches made at the Congress and the exchanges of views were of inestimable value for the successful future of the Olympic Movement and all suggestions should be studied,"

Rules on eligibility "should be brought up to date" and "assistance of Governments should be encouraged in the development of sport in their countries."

The statement added, "The IOC, IFs (International Federations) and National Olympic Committees should consider the inclusion of women in their membership and commissions," 

It took another nine years before the 400m runner Pirjo Häggman of Finland and equestrienne Flor Isava Fonseca of Venezuela became the first women IOC members.

The recommendations also proposed that the IOC, NOCs and International Federations, "should explore how they can have closer contact with athletes."

A group of Olympic champions, including six time fencing gold medallist Rudolf Kárpáti of Hungary, Soviet wrestler Mahmut Atalay, East German pole vaulter Wolfgang Nordwig, Polish pistol shooter Józef Zapędzki, British eventer Richard Meade and Romanian javelin thrower Mihaela Penes had all been invited by the Bulgarian  Olympic Committee, 

But not a single one was permitted to address the Congress.

It was not until 1981 that athletes were finally allowed to speak and it took until almost the new millennium before members of the Athletes' Commission were made full IOC members.

Although more Olympic Congresses were called for, there has not been one since 2009 in Copenhagen and it seems unlikely that any similar gathering will take place in the foreseeable future.