Is this a Pill Box?

This amazingly concrete structure is at the cross of the Greenway & the Lea River Navigational Canal - and looks very similar to some 2nd World War pill boxes.

Does anyone know the history of it, what it actually is, why it's there, what are the three concrete structures in front of it?

At the moment - it is almost as if it's the frontline of the Olympic Park - against the rest of Hackney Wick. This coupled with the electric fence they are busy surrounding the whole park with - really re-enforces the whole no-mans-land atmosphere of the site.

Aaaaaaanyway - any guesses about the concrete bunker?