This character claims to derive his orders from the line of the Brazilian Bishop Carlos Duarte Costa, who was excommunicated in the 1940s:
en.wikipedia.org/wiki/Carlos_Duarte_Costaand who went on to found his own schismatic church in Brazil
en.wikipedia.org/wiki/Brazilian_Catholic_Apostolic_ChurchEXTRACT
Bishop Carlos Duarte Costa was an outspoken critic of the regime of Brazilian president Getúlio Vargas (1930–1945) and of the Vatican's alleged relationship with fascist regimes.[5] He also publicly criticized the doctrine of papal infallibility and Roman Catholic views on divorce and clerical celibacy. Largely as a result of his outspoken views, he was moved from his post as Bishop of Botucatu in 1937 and was redesignated as the Titular Bishop of Maura (an extinct diocese of North Africa). Duarte Costa continued to criticize the government and the Roman Catholic Church, advocating policies that were regarded by the authorities as Communist. In 1944 the Brazilian government imprisoned him, but later freed him under political pressure by the United States and Great Britain.[5]
In May 1945, Duarte Costa gave newspaper interviews accusing Brazil's papal nuncio of Nazi-Fascist spying, and accused Rome of having aided and abetted Hitler. In addition, he announced plans to set up his own Brazilian Catholic Apostolic Church, in which priests would be permitted to marry (and hold regular jobs in the lay world), and bishops would be elected by popular vote.
In response to Duarte Costa, the Holy See laid against him penalty from a diocesan bishop to a titular bishop and accepted his resignation from the Diocese of Bocatu in 1937. Several years later, he formed the Brazilian Catholic Apostolic Church (ICAB). He then declared in 1945: "The Brazilian Catholic Church which is a religious society, established for the propagation of the Christianity in all the national territory, which is separated from the Roman Apostolic Church because of the errors that it has been committing since the moment when it left the catacombs, exchanging the beauty of the teachings of Christ — simplicity, humility, poverty, love of neighbor — for a preeminently mercantilistic institution, where pomp reigns, doing damage to true Christianity, which is found in the humble, the laborers, the legitimate representatives of Jesus of Nazareth."[2]
In 1949 the Brazilian government temporarily suppressed all public worship by ICAB, maintaining that the similarity of its liturgy and vestments to those of the Roman Catholic Church would result in confusion and were tantamount to deception of the public.[6] However, a few months later the churches were permitted to reopen, provided that their liturgy would not duplicate the Roman Catholic liturgy, and their clergy would wear gray clerical attire in contrast to the black clothing worn by Catholic clergy.
Duarte Costas set about to implement a number of reforms in ICAB of what he saw as problems in the Roman Catholic Church. Clerical celibacy was abolished. Rules for the reconciliation of divorced and remarried persons were implemented. The liturgy was translated into the vernacular, clergy were expected to live and work among the people, and support themselves and their ministries, by holding secular employment.[7]
Dom Luis Fernando Castillo Méndez, Patriarch of ICAN 1964-2009
Shortly after founding the church Dom Carlos Duarte Costa consecrated two more bishops, Salomão Barbosa Ferraz (August 15, 1945), and the Venezuelan Luis Fernando Castillo Mendez (May 3, 1948) Dom Salamao Ferraz acted as co-consecrator for Dom Castillo Mendez. These three bishops went on to establish similar autonomous Catholic Apostolic National Churches in several other Latin American countries. Duarte Costa personally served as consecrator or co-consecrator of 11 additional bishops, each of whom took a leadership role in either the Brazilian church or one of the other national churches.[8]
In 1958 Bishop Ferraz left ICAB to rejoin the Roman Catholic Church in which his episcopal consecration was accepted as valid. Shortly thereafter, in 1961, Dom Carlos Duarte Costa died and the ICAB underwent several years of tumult as dissensions, schisms, and multiple claimants to the patriarchal throne threw the church into disarray. After this short period, the church found stability and growth under the late Patriarch Castillo Mendez.
Some sources indicate that Bishop Luis Castillo Méndez assumed leadership of ICAB upon Duarte Costa's death in 1961, but this seems unlikely based on contemporary accounts such as Anson's.[9] What is clear is that in 1982 Castillo Méndez was elected president of the Episcopal Council, and was designated Patriarch of ICAB in 1988 and Patriarch of ICAN (the international communion) in 1990.[10] not forgetting that Patriarch Mendez was in private talks with the late Pope John Paul II in returning the Brazilian Church back to Rome. However the Council of Bishops had voted against rejoining the Roman Catholic Church. The bishops claimed that much suffering and torture had been inflicted largely at the urging of the Roman Catholic Church. Dom Luis served as Patriarch until his death. The present head of the church is Dom Josivaldo Perriera, the head of the Episcopal Council.[citation needed]
END OF EXTRACT
The fact that the so-called "Archbishop of London" describes himself as the head of the "Society of Pope Leo XIII" - it is XIII BTW, not XII - shows that the "Society" is not coextensive with the Brazilian Church, but the membership figures he gives seem to be those of the Brazilian church. My guess would be that this character does derive his Orders from the Costa line (possibly through a splinter group from the main Brazilian church), and that he claims to be Costa's rightful successor but that this claim would not be recognised by the Brazilians. There are cognate examples of episcopi vagantes being consecrated by Eastern splinter groups (the Syriac/Nestorian churches are very fragmented) and later claiming on the basis of this that they are the rightful Patriarch of Antioch etc. [see Peter Anson WANDERING BISHOPS] My guess is that this "Society" consists of Bishop Bell and a few likeminded fantasists, that he has had his picture taken with the Pope by turning up in clerical garb at a Papal audience, and that he is now inflating his own importance by presenting this as being on the same level as the talks with the SSPX.