I have some official forms to fill in, so I pop in to the central police station. From the outside, the large purpose-built edifice in the centre of Utrecht is certainly impressive in a public building sort of way, but inside it is quite a surprise. Once through the huge automated revolving door - complete with encased items of clothing advertising local shops - I find myself in a large airy glass atrium with scattered wooden benches and display stands, a bit like the entrance to a modern museum, an impression heightened by the exhibition of photographs on a police theme by a local photographer. 

The police themselves move through this space in pairs, courteous and jovial, looking relaxed and content. The tiny policewoman behind the desk, dwarfed by a beltful of regulation handcuffs, folding knife, gun and other accoutrements, is pleasant and helpful. 

There is even a visitor's toilet. As I enter the large  unisex cubicle, the door swings shut behind me and I automatically reach for the light pull, hanging dimly-seen by my side. As I pull it, everything goes pitch black, and I realise that the lights had actually already been on. Another tug reveals a room in almost complete darkness, with a select few objects glowing a fluorescent yellowish non-colour.

I've seen UV in public toilets before, fitted because heroin addicts can't find their veins under it, but who the heck shoots up in a police station? This was also the dimmest light that I have ever encountered. 

Hanging by my hand is the plastic knob of the light cord. Over to one side, the end of a tissue projects brightly from its invisible hand-towel dispenser. In front of me, two ghostly toilet rolls hang unsupported in space, and there to the side of them, glowing very faintly and identified by a fluorescent sticker on the flush handle, is the incorporeal image of a lavatory bowl.

Strangely, my urine turns out to be fluorescent.