What the...?

So there I was, taking a walk in the west Surrey countryside – south of Farnham, since you ask – when, on a quiet byway outside the picturesque village of Tilford, I came across this sign.
'By the beard of the Prophet!' I exclaimed. 'What is this?' I have a tendency to get lost on walks, but surely not this lost? The sign stood adjacent to a manned security gate, which slightly took the edge off the 'Welcome' bit, and beyond it, a long way back from the road, was a cluster of low, ordinary-looking modern buildings. Between them and the road lay a large open space that appeared to have been levelled ready for construction. What was all this doing here, in the wilds of west Surrey?
Sometimes I do wonder what the blinkin' flip is going on in this country.