Read this: Freeview Retuning Exercise Attracts Hundreds Of Complaints - ITProPortal.com

Summary: The retuning also paves the way for the gradual nationwide digital switchover as well as the forthcoming introduction of Freeview HD which will also require new set top boxes. 18 million households with 25 million television sets, set top boxes STB and other Freeview devices have had to be retuned today in order to continue receiving channels. The process will almost certainly wreck any schedule or series recordings. - itproportal.com