In the PCI he was known as a specialist in trade union matters and rarely took a stand on international issues. When Michel Pablo, the secretary of the Fourth International, raised the question of entrism sui generis he took no stand until his field of operation in the trade unions was threatened. He then backed the PCI leadership around Bleibtreu and Favre.
However in time Lambert moved against Bleibtreu and Favre and they were expelled from the small PCI. By this time, 1952, the PCI had split into two mutually hostile groups on the question of entrism sui generis and the associated perspective of hundreds of years of deformed workers states propagated by Pablo. Despite their having led the struggle against Pablo this made no difference to Lambert in expelling Bleibtreu and Favre.
Fully in control of the PCI by 1954 Lambert forged an alliance with the Socialist Workers Party (USA) and joined with it in the International Committee of the Fourth International. This alliance would last for nearly a decade at which point the SWP (US) and its international faction fused with the International Secretariat of the Fourth International, within which Pablo was now marginalised, to form the United Secretariat of the Fourth International.
Lambert was left in 1963 to continue the ICFI in an alliance with the Gerry Healy led Socialist Labour League based in Britain. The much shrunken ICFI consisting at this point of the SLL, Lamberts Organisation Comuniste Internationaliste (the PCI as rebranded in 1966) and very little else.
Under his real name of Pierre Boussel, Lambert was candidate at the presidential election in 1988. He gathered 116 823 votes (0.39 % of validly cast ballots).
Lambert began his activity as a Trotskyist militant before the Second World War when he was a member of the Internationalist Workers Party (POI) led by Raymond Molinier.
Fully in control of the PCI by 1954 Lambert forged an alliance with the Socialist Workers Party (USA) and joined with it in the International Committee of the Fourth International (ICFI).
Lambert was left in 1963 to continue the ICFI in an alliance with the Gerry Healy-led Socialist Labour League, based in Britain.
Pierre, S.V., Duran, M.J., Carr, D.L., and Pressley, T.A. (2002) Structure/function analysis of NA+-K+-ATPase central isoform-specific region: Involvement in protein kinase C regulation.
Duran, M.J., Pierre, S.V., Carr, D.L., and Pressley, T.A. Role of the isoform-specific region of the Na,K-ATPase catalytic subunit.
Duran, M.J., Pierre, S.V., Carr, D.L., and Pressley, T.A. The isoform-specific region of the Na,K-ATPase catalytic subunit: Role in enzyme kinetics and regulation by protein kinase C. Biochemistry 43, 16174-16183.