An official BBC complaints ruling has stated that the Panoroma programme that made headlines at the time about Wi-Fi being dangerous was "misleading".
Panorama was criticised for exaggerating the grounds for concern and wrongly suggesting that Wi-Fi creates high levels of radiation.
An expert who appeared in the programme, Professor Michael Repacholi, complained that the scientific issues had been presented in an unbalanced way, and that the treatment of his own contribution to the programme was unfair.
"The programme included only one contributor (Professor Repacholi) who disagreed with Sir William, compared with three scientists and a number of other speakers (one of whom was introduced as a former cancer specialist) who seconded his concerns", the ruling said.
"This gave a misleading impression of the state of scientific opinion on the issue."