We perhaps forget that the Severn Bridge was a huge leap forward in bridge design. Britain led the world in this field. Every subsequent long span suspension bridge built anywhere in the world has aped this British design.
I thought the context of the design was rather muddled. Only a brief mention of the Forth Bridge, which was (and still is) longer. That was being designed when the Tacoma Narrows bridge collapsed, leading to a lot of wind-tunnel testing (to make sure the air flowed through the girders nicely) and several design additions. Almost no mention either of the Humber Bridge, which finally beat the Americans for length.
The point of these three is that all were designed by Freeman Fox and Partners, who themselves weren't named until right at the end. And those interviewed worked for Freemans and for various contractors, who weren't named, and how these companies collaborated was never explained.
But it was a very interesting programme.
Incidentally, Freeman Fox and Partners became part of Hyder Consulting, design engineers for - guess what - Manchester Victoria and its new roof! And they are now part of Arcadis NV.