as Bruce and Chris said ...
FWIW Clostermann interview clip from 1975 talking about these events (which he states took place on 21 April) and a partial English transcript..
http://falkeeins.blogspot.co.uk/2011...french-tv.html
According to 122 Tempest Wing's war diary for the 20th, "
a good day, the 'mad Frenchie' got another two Fw 190s.."