Here's a link to an interesting and informative one hour plus radio interview with Brian Camden from Hardened Structures USA.
The exact same interview as above goes from "28.40 mins to 1 hr 37 mins" in the below full length radio interview You Tube clip which was recorded on the 18th September 2013.
NB: Hardened Structures does not have a stance in regards to the radio show "Late In The Midlands" and or the views expressed other than those of Hardened Structures.