UPDATE The picture fault affecting BBC One HD on Freeview HD in Northern England has been resolved.
Following a campaign by various AV Forum members, news of the fault reached the BBC's Andy Quested. Posting on his recent blog, he advised viewers that the fault originated from the Winter Hill transmitter and other transmitters fed from it.
A faulty encoder, which appears to have been the cause of the fault, has been replaced.
In his reply, he stated: "I want to thank my colleagues in Distribution and R&D who acted on this so quickly."
Later on, he added: "The fault was quite subtle so the automated and brief visual checks carried out missed it."
The fault resulted in grainy pictures with vertical lines on BBC One HD and raised fears among some viewers that the process for complaining is ineffective, with viewers unable to get past standardised cut-and-paste responses from customer service staff.
Acknowledging the breakdown of communication, Andy Quested admitted: "Actually the biggest and more worrying failure was why the reports
coming in from people such as yourself failed to get through the people
who could check more closely - agreed this should have been picked up
and acted on in within 24 hours."
The Freeview HD multiplex has limited regionality. The fault appears to have affected all Freeview HD viewers who receive the version of the multiplex that carries ITV HD Granada on Freeview HD channel 103. That includes Freeview HD users in the Yorkshire, Tyne Tees and Border (England) regions.
updated 17:00 20/03/2013