A few weeks later I went to a big bookstore and had to check an insect guide. And found it. The insect was named Roodkopvuurkever in Dutch. Vuurhaantje is probably an unofficial name used at some places in The Netherlands. It's a Cardinal beetle. Scientific name Pyrochroa serraticornis. In English not to be confused with the other beetle that is named Cardinal beetle. Pyrochroa coccinea has a black head and is a bit more common than the red headed version I observed.
There was a whole bunch of these beetles where I was strolling through the countryside near Leiden in The Netherlands. This is the season or month to spot Cardinal beetles!
Cardinal beetle - countryside near Leiden, The Netherlands
Originally uploaded by David d'O