Yes something cows drink out of. In the middle of London? Yes again. Until late in the 19th century animals were driven in to the nearby Smithfields Market. The market is still there but it is carcasses that are brought in these days. Back when live animals were on their way to market these drinking troughs were strategically placed along the way.
Interesting that people were drinking gin and beer as the water wasn't drinkable.
Maybe the cows had gin as well. Gin was produced a few metres away from this trough so maybe daisy had a jolly end.