He went
to Art School from 1962 to 1967, took
part of the
‘Provo’ movement, the Dutch equivalent to the
Beatniks and, in 1966, created a political cartoon newspaper "God,
Nederland & Oranje" 
where Picha and Roland Topor were published. The newspaper was censured
(this is quite usual with Willem’s work).
Soon after
he arrived in Paris, he worked for the early issues of "l’Enrage" 
,
"L’Hebdo Hara-Kiri", and then for "Charlie-Hebdo". 
His cartoons,
strips and comics are directly inspired by the world news of the time and
his chronicles depicts the current cultural life (both pretty much emphasizing
graphic expression): "Revue de Presse" and "Chez les Esthètes" for
"l’Hebdo Hara-Kiri" then "Charlie-Hebdo", "Chez les Esthètes" for
"Charlie Mensuel" and "Images" in 
since 1981.
His strips
and drawings for the press were published – among others – in Phosphore,
Bijster 
,
Hitweek, Model-Peltex, Cocktail Comix, Provo 
,
Métal Hurlant, Je Bouquine,
Rock
Hardi, Fluide Glacial
,
Bizarre Sex(Kitchen Sink 1972), Action (1969), J'accuse
,
La Grosse Bertha
,
50
millions de consommateurs, Zéro, Rip
Off Comics, Anathème, Viper, Stripburger,
Vrij
Nederland, Opus International, l’Echo des Savanes (deuxième
période), Hara-Kiri 
,
Lard-Frit 
,
Rouge,
Une minute de Silence ("Journal muet international"), Réciproquement,
Aloha
, l’Horreur
est Humaine, Zoulou, Rigolo (la famille "Surprise"d'un jeu des 7 familles),
Réciproquement, Tante
Leny Presenteert!, BD-l'Hebdo de la BD
,
Passages 
,
Le Citron Hallucinogène, Politis,