Yeah, they're building a new development of flats right next door. I saw photos of the gas storage tanks.
I was there on a drizzly day in early March -there were maybe 2 dozen people in the whole place, so I could wander around at my leisure. I'm sure it gets a lot busier in the Summer & judging from the educational exhibits, probably gets a lot of school trips & foreign students. Entry was something like a tenner, (I paid by card & didn't actually pay attention to the price), but parking was free, though only room for about 20 cars. Nice little café with proper home made food & a nice cup of tea. I could happily have stayed there all day, just watching the engines turning. I thoroughly enjoyed it -one of those hidden little gems that are all over the place in London. Well worth a visit if you're in the big city.
Nice pub next door too.