GO
I think you only need an HD box rather than an HD subscription.
Sky Catch Up webpage has been launched. It will be part of Anytime+ and available only to Sky+HD subscribers.
http://www.sky.com/products/ways-to-watch/anytime-plus/catch-up?DCMP=DMC-SkyCOM_catchup
http://www.sky.com/products/ways-to-watch/anytime-plus/catch-up?DCMP=DMC-SkyCOM_catchup
I think you only need an HD box rather than an HD subscription.