at http://www.sgdk.nl" onclick="window.open(this.href);return false; you can go to databases and to feoreign registers. There you can see all civil foreign visitors with pic. In the list are 5 S61's.
I am pretty sure that the G-BDOC is one of the 2 currently at De Kooy. And after a phone call to the TWR the other winning number is G-BIMU.
Sorry that the based aircraft list is not up to date...