I was very envious when JV showed me this in his garden. I have been on the lookout for disused cast iron water tanks that may be coming out of old buildings exactly for the use here – probably different plants but definite same use (beauty, eye, beholder and all that).
This cast iron tank is stamped BO (Board of Ordnance) 1836 and was found at Murphy Barracks in Ballincollig after it was sold and undergoing development.