With the launch of BBC2HD on Monday 26th March (http://www.uksatellitehelp.co.uk/2013/02/19/bbc2-hd-will-launch-in-march/) , the BBC are also using this for a small channel reshuffle, which will mainly affect Sky HD users.
On Sky HD BBC1HD and BBC2HD will be moving to new channel numbers, located next to each other, rather than being separated.
So on SkyHD:
BBC One HD, currently on Sky channel 143, will move to Sky channel 141.
BBC Two HD, currently the BBC HD Channel on Sky channel 169, will move to Sky channel 142.
BBC Alba, currently Sky channel 168, will move to Sky channel 143.
which finally makes some sense rather than having their two HD channels separated on the Sky Guide!
On Freesat HD BBC One HD will remain on Freesat channel 108.
BBC Two HD will replace the BBC HD Channel on Freesat channel 109
Although the changes should, on Sky and Freesat boxes, be automatic, it may be wise to check any recordings in your planners for these channels, to make sure they are still scheduled.