In 1982 the municpality of Hoensbroek was merged with Heerlen.
Sierksma's Nederlands Vlaggenboek, 1962 [sie62]
has:
"Description: Nine equally wide horizontal stripes white and red, with
in the center, high seven stripes, the municipal arms.
This flag is not official, but is being used since 1958 by the municipal
council. The white and red stripes are derived from the little shield on
the Coat of Arms. I've used the Koffie Hag image from Ralf
Hartemink's site. The saint is John the Evangelist.
Jarig Bakker, 25 Jun 2003
Shipmate has a flag with 9 equally wide vertical stripes of white and
red, and mentions the date 1938, so probably a parading flag on the occasion
of Queen Wilhelmina's 40 years reigning jubilee.
Jarig Bakker, 25 Jun 2003