Certainly try retuning, but I have also lost BBC4 HD and BBC News HD and a couple of others, and can't restore them despite several retunes.I did some research on line and it seems that Crystal Palace transmitter has changed some frequencies and that an old 'Group A' aerial will no longer receive some channels. The information I found got too technical for me, so I think I shall just have to do without the HD versions and hope things resolve themselves. Either that or fork out for a new aerial...If you want to know more, try Googling 'BBC4 HD disappeared' and you'll find several links. Some are quite old (this has obviously happened before, and to transmitters in other parts of the country) so look for 2018 and Crystal Palace.
Lorna Dodd ● 2845d