The traditional distinctive buildings we see everywhere are very much changed inside.
I visited one a few years ago, on telecom related business. In spite of my knowledge, I was shocked to find the building almost completely empty, apart from the digital gear and the MDF.
All the Strowger switches gone of course.
I have just had a Google for what I could have seen. Didn't really find what I was looking for but found an interesting history of Redhill/Reigate.
It's a bit long. Scroll down and look at the piccies if you have a short attention span.