Hi DiS. I moved house a couple of weeks ago and this thing is in my bathroom between the toilet and the sink:
I just assumed it was a bidet initially (though did not attempt to use it for this purpose) but it's since come to my attention that the tap points straight down, thus making it useless for bum cleaning. My only other guess is a font for baptising children. Help me out. I bet you all grew up with this kind of thing in your middle class palaces.