Oh yes, the last reservoir to be built in England is Carsington Water in the middle of Derbyshire (which is not in Southern England). Planning started in the late 60s, construction in 1979 and it was opened in 1992. The building of it took a lot longer than it was supposed to as there was a dam collapse during construction in 1984.
I'll guess 1990 or 1991. I'm likely reading too much into this as you said he had a distinctive speaking style but something about how he said it sounds really recent to me.
