I knew Handman had to be referring to Time of the Doctor. I thought it was obvious by the way he described his family’s confusion. I guess it could’ve been the Husbands of River Song, but for some reason I was just thinking of Matt Smith. Personally, I think Christmas Specials would work better as post-regeneration episodes, since it’s more climactic to have the regeneration episode be the series finale. Wanting Christmas Specials to be accessible is just another reason to add on to that.