Later on, he studied with Guido Vecchi in Götheborg, Giuseppe Selmi in Rome, and with William Pleeth in London.
He has performed under many conductors, including Sir Colin Davis, Maxim Shostakovich, Neemi Järvi, Evgeny Svetlanov, Gennadi Roshdestvensky, Kurt Sanderling, Rafael Frühbeck de Burgos, Rostropovich, Herbert Blomstedt, Seiji Ozawa, Yuri Temirkanov und Esa-Pekka Salonen and many others.
[2] In 2002 he founded the Michelangelo String Quartet in which he regularly performs worldwide, together with Mihaela Martin, Daniel Austrich and Nobuko Imai.
[3][4][5] Helmerson for many years has taught at the Hochschule für Musik und Tanz Köln, as well as at Escuela Superior Musica Reina Sofia in Madrid.
Also to a great critical acclaim, he released two cello concertos by Shostakovich, along with conductor Valery Polyansky and the Russian State Symphony Capella.