Boss, the documentary was inaccurate, and most of the letters which C4 claimed to have were not what they purported to be. They basically accused DH, BOAC and the ministry of criminal negligence.
The broadcasting standards comission upheld complaints that it was unfair, in my opinion it verged on libellous. Your aquaintance has good reason to be upset, as did those who designed and built the comet.
There is a very thorough article in the May 2004 issue of 'The aerospace professional' (RAeS) which details the reasons why those letters had nothing to do with the loss of yp or yy, and is really worth reading if you saw the original programme.