[Stuart]

The HD tag only ever appears in the EPG title for most channels on that format.  The two main BBC channels don't have DOGs, so there was nothing to change and they stopped using the 'HD diamond' or even mentioning it in promos many years ago. On the Nightlight service, BBC One list regional programmes as 'This is BBC One SD' together with the new RSOD, so perhaps they're leading the way.

ITV1 reduced their +1 SD services some time ago, but probably retain the main SD ones for advertising purposes, much the way as C4/C5 do.

Sky haven't mentioned HD for many years in their promos, but have it in their EPG channel names. They have offered free upgrades to people viewing on SD STBs, but some people probably don't realise that they can watch HD channels on an SD set if they have a SCART socket (probably previously used for a VHS or DVD player). Obviously in those circumstances they wouldn't have an HDMI input or see anything other than SD quality.

It took a while for broadcasters to stop mentioning 'COLOUR' back in the day, so I guess that not harping on about HD has been quite a rapid progression.

Many channels will never upgrade to HD broadcasts, so the necessity to maintain the differential with SD channels will remain for some time.