I don't really care what it cost; I'm sure people who play the lottery paid for it, so I just can't get as interested about the cost as I did when such things were funded out of our taxes.
And actually I thought it was a really clever idea, and grabbed a lot of attention. Amusingly, a Gormley was then stuck on top, providing an interesting counterpoint and much discussion about whether one could have just too much of a good thing....
The project was sponsored by Bloomberg, according to the NT website. They support lots of new art things.
I also liked the idea, and I think it more or less worked, though there was something a bit desperate about all that watering they were doing at the top right corner throughout May, even during rainy spells. Turf on clay smeared onto a concrete wall was never going to be easy.