Matthew King has established a reputation as one of the most inventive and exciting modern British composers. His major works include The Snow Queen (1992) a chamber opera premièred with Jane Manning in the title role, Jonah (1995) a festival opera premièred in Canterbury Cathedral, Gethsemane (1998), an oratorio premièred at the Spitalfields festival, and On London Fields (2004) an opera written in association with the Academy of St. Martins in the Fields and the Hackney music development trust, premièred at the Hackney Empire. On London Fields received the Royal Philharmonic Society Education Award in 2005. His cantata 'Hear our voice' (written in collaboration with Jonathan Dove) has been shortlisted for the British Composer Awards 2007. He is currently writing a cello concerto for Natalie Clein and a chamber opera for the Kammermusik festival in Nuremberg. Matthew King has taught composition at the Yehudi Menuhin School, and is currently a composition professor at Guildhall School of Music & Drama.

His work has received considerable critical acclaim. The Independent has described it as “clever, sharp and fresh, bursting with memorable melody” and Matthew himself has been called a composer “who writes not only credibly and well but with immediate, engaging charm”. The Financial Times described the music of his opera project on Isambard Kingdom Brunel as “immediately attractive, richer and more varied than the long littleness of Adams's Nixon in China”.

Portobellissima was commissioned by the Portobello Orchestra with funding granted by the Kensington and Chelsea Arts Council. Ideas for the work were generated in an orchestral workshop with the composer who then composed them into a short overture.

The piece divides into two halves: the first half is built on various motifs which first originated as improvisations from members of the orchestra during the workshop, several of them rather Spanish in character. The Portobello road takes its name from the notorious capture in 1739 of the Panamanian town of Portobello by the British pirate Edward Vernon but it has also been home to a significant Spanish community for many years. Jimi Hendrix (who lived in Portobello Road) is briefly quoted. So too is the Socialist anthem 'The International' because of the area's historic associations with left-wing and anarchist politics. The second half of the piece is built around a recurring march-like theme in the Elgar tradition. The melody resembles a recurring street call - 'Portobello' - announced first by the violins, and worked into a canon for the whole orchestra.

Portobellissima! was performed by the Portobello orchestra on the 15th December 2007.  The conductor was Anthony Weeden.