Peter Glossop was one of the pre-eminent baritones of the Sixties and Seventies and specialised in such testing roles as Rigoletto, Iago, Rodrigo (Don Carlos) and Count di Luna (Il trovatore). Although he was often heard in London — at both Sadler’s Wells and Covent Garden — he was one of the few British singers successfully to blaze a trail abroad and he appeared at all the world’s leading opera houses.

On stage he combined a rugged boldness with a robust vocal delivery; and he preserved a wonderful sense of Verdian line with a sharp understanding of melodic presentation.

He also sang Puccini, making his Metropolitan debut as Scarpia, and was a particularly memorable Tonio in Pagliacci. He was an uncompromising interpreter of the title role of Billy Budd and a memorable Balstrode in Peter Grimes. It was after a performance by Glossop of Pagliacci that Herbert von Karajan (never an easy maestro to impress) offered him Iago at the 1970 Salzburg Festival. Glossop had a wonderful legato but when he delivered, for example, Iago’s famous Credo, there was villainy and treachery in the voice.

Peter Glossop was born in 1928 in Sheffield. On leaving school he worked as a bank clerk but in the evenings he was an enthusiastic member of the Sheffield Operatic Society, making his stage debut with it in Tales of Hoffman in 1949. He started lessons with a local teacher, Eva Rich, and was a finalist in the 1952 Great Caruso Contest. He joined the Sadler’s Wells chorus that year but his outstanding vocal talents were recognised and he was soon offered minor roles with the company; by 1955 he was a company principal.

Although he made auspicious debuts in several Verdi roles (Rigoletto most notably), conductors at Sadler’s Wells, such as Colin Davis and Alexander Gibson, also cast Glossop as Scarpia (Tosca), Gerard (Andrea Chénier), Zurga (The Pearl Fishers) and the title role in Eugene Onegin. He sang Gugliemo in the company’s 1957 production of Così fan tutte and also that year learnt Sir Tristram in the seldom-performed Martha when a colleague was indisposed.

It was a period of rapid learning for Glossop and his ability to study was rewarded when he won the first prize at the first International Competition for Young Opera Singers in Bulgaria in 1961. This award started Glossop’s international career, and amid some recriminations in the press he joined the Royal Opera and sang Demetrius in Britten’s A Midsummer Night’s Dream at Covent Garden and at the Edinburgh Festival.

Covent Garden then booked Glossop for the following season, and he appeared in revivals of Aïda and La bohème. In 1964 he stepped in to save the Royal Opera in a difficult situation. A new production of Rigoletto was scheduled with Franco Zeffirelli directing and Georg Solti conducting: the first night had to be postponed as Geraint Evans (singing the title role) had vocal problems. When the production did reach the stage it was clear that the role did not suit Evans’s voice. Solti asked Glossop to take over immediately and he learnt the role and the finer points of the production in a matter of days.

In November 1964 a prestigious new production at Covent Garden by Luchino Visconti of Verdi’s Il trovatore was to be conducted by Carlo Maria Giulini with a stellar cast. Glossop’s account of di Luna was widely praised, and he now was among the first-choice baritones for new productions in the international houses. For example, he enjoyed a triumph at his La Scala debut the following year in Rigoletto.

In 1965 Solti courageously scheduled a Ring cycle sung entirely by members of the company. David Ward was Wotan, Amy Shuard Brünnhilde and Glossop a resounding Donner. Solti at the curtain call on the last night was heard to say: “I feel very good about the English singers.”

It is thought that Karajan was in the audience when Glossop sang a year later in Pagliacci at La Scala. He was captivated by his performance, the musicality of his voice, and his stage presence — in an interview he said of Glossop: “Those pale blue penetrating eyes . . . panic and anger are not far below the surface.” In 1970 Karajan cast Glossop alongside two of the great stars of the era — Jon Vickers as Otello and Mirella Freni as Desdemona — in Karajan’s own epic production of Verdi’s Otello at Salzburg. The maestro was setting up such grand productions in tandem with a film and a recording to defray costs, and enormous pains were taken over rehearsals and the studio recording.

Glossop received critical acclaim for his Iago (“a consummate histrionic performance of great strength”), and the production was well received in Salzburg. Some, however, felt that the film looked mannered and too “stagey”. The recording has won acclaim and is still thought one of the finest versions of the opera.

Glossop then sang extensively in London and in all the European and American houses. In 1979 he reduced his commitment to the Italian repertory and explored German opera. He sang the title role in The Flying Dutchman with English National Opera North that year in Leeds and then Mandryka in Arabella at English National Opera and Pizarro in Fidelio at the Met.

His recordings were numerous, dating from a Macbeth with Rita Hunter in the Sixties through a distinguished Billy Budd under the composer and then in 1967 the first recording by Davis of Berlioz’s Les Troyens with Glossop providing a strident Choroebus.

Glossop was a demanding artist; he himself once said: “They say I am a troublemaker, but I will not go against a composer or the words of a piece.” Glossop certainly preserved contempt for producers and opera houses that “get away with excesses. Their presumption that they think they are better than Verdi/Wagner really annoys me.”

At his most powerful Glossop was a wonderfully dramatic baritone, blessed with a vocal intensity that brought a character to life with a strident honesty. His singing was always forthright, committed and bold.

His career continued well into the 1980s when he retired to the West Country to teach. He was an honorary doctor of music at Sheffield University. He had a passion for jazz and amassed a huge collection of Dixieland jazz records.

He married first the soprano Joyce Blackham in 1955 (dissolved 1977) and second Michele Amons in 1977 (divorced 1986). He is survived by the two daughters of his second marriage.

Peter Glossop, operatic baritone, was born on July 6, 1928. He died on September 7, 2008, aged 80