This is the answer about my 'geese question' that I received today from fellow Dutchman and bird expert Jan Harteman (this is his website - check it out - also in English!)
"Thanks for your e-mail. I’ve had a look at the picture of the geese. All these geese, without exception, are tame / domesticated geese. That means that they are originally ‘home geese’, that were kept and bred for production. There are different known races and they are all descendants of the grey goose (Anser anser) and sometimes of the swan goose (Anser cygnoides). Some of these races are predominantly white, others coloured or grey / greyish.
Now and in the past some of these geese escaped from farms or they were brought to parks. These geese become wild again in polders or city parks and they mix with their undomesticated ancestors. That is why you can see big groups of tame geese between grey geese. Or, as depicted in your photograph, a complete group of tame geese. The one with the grey head could be a mixture of several tame geese races, or probably a mixture of tame geese / grey geese. It is not uncommon that one of the geese looks a little bit different."
Thanks, Jan! I hope my translation of your answer is accurate - hopefully it will still make some sense to my foreign blog readers. I like birds, but I am already happy that I am able to tell the difference between geese and swans... This goose with a grey head just caught my eye and now he is my favourite (I just have a weak spot for all people and animals who stand out in a crowd. Dare to be different - that's what I say!) Thanks also for all your educational work and you willingness to share your knowledge. Maybe you can also have a look at my question about swans and moorhens in my earlier postings on this blog... if you have some time left.