After some playing around with locale settings i finally got my UK Freeview digital stream box to switch on and off with the "XBOX ON/OFF" commands.
It appears when set to US locale that the XBOX ONE is capable with the current firmware/OS to talk to PVR/DVR and set top boxes from the uk. Simply go to the manual IR codes setting and type in your box. You will have to spoof a US Zip code ( 902010 or somthing ).
I have a Digitalstream DVR box, i was able to now turn on/off the box, pause and restart live tv ( if your DVR has timeshift ) and even select channels. ( Well kinda! ) If you say "Xbox channel NBC" for example it sent me to uk Channel 004. So the facility is there, we just need the freeview listings for each uk region within Oneguide that are pulled from that TV guide service and we are away. These settings work only within US locale. When changing back to uk the on/off toggle still works, but the other stuff is then disabled. It seems all the OS does is disable the channel selection ( and play / pause etc ) but just remove the settings from the menus!