Although he was widely known, he was never a major force in the Dutch political landscape,[1] partly because of a cordon sanitaire imposed by Prime Minister Ruud Lubbers's third cabinet.

Johannes Gerardus Hendrikus Janmaat was born on 3 November 1934 in Nes aan de Amstel in North Holland, as the oldest of nine children in a traditional Roman Catholic family.

[1] After graduating in 1954, Janmaat started a study in aeronautical engineering, but had to drop out two years later after his father could no longer afford the tuition fees.

[1] In 1980, he read an article in Vrij Nederland which drew his attention to the recently founded extreme-right Centre Party (CP).

[1] Politically, the party did not differ greatly from the CP, except that it was strongly centered around Janmaat, to prevent another power struggle.

[1] Major political parties changed their response to Janmaat and his views: rather than actively ignoring him they also started openly addressing the issue of immigration.

[1] Disappointing economic growth, unemployment and government cutbacks could not be addressed while large numbers of immigrants were flowing into the country.

[4] He was often accused of committing acts of hate speech, and received fines and a conditional felony prison sentence for incitement to hatred and discrimination against foreigners.

He argued that Ernst Hirsch Ballin should not be allowed to hold a high office because of his Jewish heritage[8] and said he was not saddened by the sudden death of political opponent Ien Dales.

[9] Meindert Fennema, Emeritus Professor of Political Theory of Ethnic Relations at the University of Amsterdam, argued in 2006 that Janmaat was convicted for statements that are now commonplace[3] due to changes in the political climate (caused in part by the September 11 attacks, and the assassinations of Pim Fortuyn and Theo van Gogh).

[8] As the first public spokesperson who tried to put the topic of immigration on the Dutch political agenda, Janmaat has been mentioned as a forerunner of Pim Fortuyn, Geert Wilders and Thierry Baudet and their parties Leefbaar Nederland, Partij voor de Vrijheid and Forum voor Democratie, which booked greater electoral successes in the following decades.