Blanken studied in Amsterdam, with Hermann Schey among others. He made his debut as a concert tenor in a church Edam in 1954; concert (oratorio above all) would always remain the core of his repertory, although he also sang some opera from 1957 onwards at the Zuid-Nederlandse Opera, and from 1959 at the Nederlandse Opera: Belmonte, Don Ottavio, Almaviva, Baron Kronthal (in Lortzing's Wildschütz).
Above all in the 1950s, he sang some prominent Bach and Händel oratorio performances with the Concertgebouw Orchestra, under Bernard Haitink and Anthon van der Horst, respectively. Other than that, he sang a lot in outlying locations, outlying at least as far as Bach oratorios are concerned: the Middle and Far East, South Africa, Indonesia, Israel (where he premiered both Bach's Johannespassion and Händel's Messiah).
Blanken sang into the late 1970s, and became a successful voice teacher. His singing is the proof that it's perfectly possible to be a tenore da circo even in the least circus-like of all musical genres, baroque oratorio.