If you're ordering Season 2 on Blu-ray from Canada or USA, don't bother ordering the Christmas special -- it's included in disc 3 of the blu-ray set. I notice that another reviewer has confirmed it also is included in the North American DVD Season 2 set.
It is shameful that Amazon hasn't listed the contents of Season 2 (and Season 1) sets -- both sets included special features as well as the Christmas special on season 2. That is useful information for consumers to have, information which saves money if you've already ordered the full season or are planning to do so. I was on the verge of ordering this separate Christmas special disc, but fortunately decided to wait until getting the season 2 set. The first thing I did before viewing season 2 was to pop each disc into my player to check out the menus, where I happily discovered the Christmas special on disc 3. But if I'd paid attention to the reviews that mention the special isn't included in the UK sets, and took seriously the notation on Amazon that this PBS edition is "original UK edition" (which it does say on the cover of the actual set that arrived), I might have been misled into ordering the Christmas special separately, needlessly spending extra money for an extra disc I wouldn't need.
It is for this reason, and this reason alone, that I am giving this item only one star (I gave the season 2 set five stars in my review of it, where I repeat my point about the Christmas special and name the special features that are included. The one star may also attract reader notice to this review and save people some money.
Come on Amazon, pull up your socks and list the contents on ALL the sets that you sell, please! Both BD sets (seasons 1 and 2) are superb products and deserve better advertising than what you've giving them.
I look forward with great anticipation to season 3 and beyond, if it continues beyond!