After reading the Thread "The Dream is Over" I checked out the body's that TDI belonged to as stated. The BRITISH PERFORMANCE & RACING INDUSTRY ASSOCIATION has only two members TDI and Cosworth(who TDI sell there goods). As for the MIA, any one can join.
http://www.bpria.com/
http://www.the-mia.com
Below is a snippet from the thread.
" For those who are unaware, we are quite well established and reasonably well known in the tuning industry. We take our work and the interests of our clients very seriously which is why we are one of the very few companies in this industry who have signed up to the codes of conduct issue by the Motorsport Industry Association, and the British Performance and Racing Industry Association. I am not aware of any other Tuners that have done this."
BEWARE Never judge a book by its cover!!