Oldham was born John Stephens Oldham in Accrington, Lancashire, the son of Thomas Oldham and his wife Harriett, née Stephens.
He had an elder brother, George, and a sister. As a child, Oldham was a boy soprano in demand for over five years in
oratorios (including Sullivan's The Golden Legend and The Prodigal Son), concerts (including
"Neath My Lattice" from Sullivan's The Rose of Persia), and pantomimes.
As a young man, he worked as a bank clerk and sang in amateur operatic societies.
He made his debut on the professional adult stage in 1914, as Julien in The Daring of Diane, an operetta by Alfred Anderson and
Heinrich Reinhardt, presented at the London Pavilion. He made an immediate mark: The Observer said that he "has an exceptionally
charming tenor voice, uses it with fine art, and acts with engaging simplicity and sincerity." Later that year, at the Lyric
Theatre, he played Bumerli in The Chocolate Soldier, in which he also won excellent notices. At the end of that year,
after the outbreak of World War I, he joined the Scots Guards, a year later was commissioned in the East Lancashire Regiment
and was awarded the Military Cross for gallantry in Macedonia in 1918. During the war, he formed a concert group to
entertain his fellow servicemen, also producing The Chocolate Soldier not far from enemy lines.
Oldham was demobilised in July 1919 and joined the D'Oyly Carte Opera Company the following month,
when the company opened its first London season in over a decade. He immediately assumed the leading Gilbert and Sullivan tenor
roles of Alexis in The Sorcerer, Lord Tolloller in Iolanthe, Cyril in Princess Ida, Nanki-Poo in The Mikado, Colonel Fairfax in
The Yeomen of the Guard, and Marco in The Gondoliers. The following year, he also took on the roles of Ralph Rackstraw
in H.M.S. Pinafore, Frederic in The Pirates of Penzance, and Richard Dauntless in Ruddigore. In 1921 he exchanged Cyril for
Prince Hilarion in Princess Ida.
Oldham left the D'Oyly Carte company in 1922 to star in a great number of musicals and operettas during the 1920s at the Theatre Royal,
Drury Lane and other West End theatres. His first musical was Whirled into Happiness at the Lyric Theatre, as Horace Wiggs, where his
leading lady was his future wife, Winnie Melville. They married in 1923. She would later join the D'Oyly Carte Opera Company as
a principal soprano. Oldham wrote, "The sheltered, almost student life of the D'Oyly Carte Opera Company gave place to the hard
glitter and luxury of the West End theatre – a world of restaurants, supper parties, and all the trappings that went with London
theatrical life between the two wars". Other musicals in which Oldham starred included Madame Pompadour (1923, as Rene),
The Merry Widow (1923, as Camille), and Rose Marie (1925, as Jim). In 1927, Oldham and Melville starred together in
the European première of The Vagabond King, he as François Villon, and she as Katherine de Vaucelles. They separated in 1933
and later divorced, and she died in 1937.
Oldham returned several times to D'Oyly Carte, appearing in the 1929–30 season and on tour in his old roles of Ralph, Frederic,
Tolloller, Hilarion, Nanki-Poo, Fairfax, and Marco. In the 1934–35 season, he played these roles on the company's first major
American tour in the 20th century. In 1936, during the company's season at Sadler's Wells, he played Hilarion, and he was
leading tenor in the 1936–37 season, which included another long American tour. Oldham's presence was a condition demanded
by the American promoters. During this tour he and Sylvia Cecil were seconded by the company for one night to sing "Prithee,
pretty maiden", from Patience at President Roosevelt's inauguration party at the White House.
Oldham later played in many musicals and plays, including The Song of the Drum at Drury Lane, as Captain Anthony Darrell
(1931). He appeared at the Royal Albert Hall as Chibiabos in Hiawatha in 1938, conducted by Malcolm Sargent.
After 1948 he developed a career as a Lieder singer and lecture-recitalist and later as a character actor in non-musical plays.
His last role in London was Dr. Stoner in the Agatha Christie play Verdict (1958). Between 1934 and 1957, he also appeared in
In 1940, on the 29th of February, the character Frederic came of age, as described in The Pirates of Penzance, Act II. This was a
significant date for any G&S tenor. In New York, the Gilbert and Sullivan Society journal, "The Palace Peeper", marked the
event by publishing an original ode to Frederic, in which Oldham was honoured as the archetype of the romantic Frederic. A member
of the Gilbert and Sullivan Society in London from 1924, Oldham was elected Vice-President of the Society in 1947.
During his last decade, Oldham lived in retirement in Hayling Island, Hampshire, but he often visited London. He acted as compère for
the D'Oyly Carte company's last night revelries at the close of its 1961–62 London season at the Savoy Theatre. He died in
Portsmouth in 1968, just before his 81st birthday.
Oldham played leading tenor roles in nineteen full and abridged HMV Savoy opera recordings, as follows: Defendant in Trial by Jury
(1928), Alexis in The Sorcerer (1933), Frederic in Pirates (1920, 1929 and 1931), the Duke of Dunstable in Patience (1930),
Earl Tolloller in Iolanthe (1922 [part] and 1929), Hilarion in Princess Ida (1924 and 1932),
Nanki-Poo in The Mikado (1926 and 1936), Richard Dauntless in Ruddigore (1924 and 1931), Colonel Fairfax in Yeomen
(1920, 1928 and 1931) and Marco in The Gondoliers (1927 and 1931).
He also made numerous recordings of songs, musicals and operettas.
He also appeared in several films between 1934 and 1957, including The Broken Rosary (1934), as Giovanni; Charing Cross Road (1935),
as Jimmy O'Connell; Melody of My Heart (1936), as Joe Montfort, and Dangerous Exile (1957), as William.