@DavidDetroit as @Pavros says, the kit finished at 1.020 but gives 7.5%. In the new Brewferm packaging the Christmas ale is rebranded as Winter Ale. There is no added sugar in ferment and 49g (for 7l) priming sugar at bottling. They have reduced the fg to 1.015I think that this is only for this particular kit - it used to finish at 1.020 and instructed you to bottle with no priming sugar. The last time I made it, the instructions said it would finish at 1.010/12 (can't remember exactly) and gave an amount of priming sugar to use. They must have changed the yeast in the kits. Not sure what the current instructions are as I haven't made it for 4 or 5 years.
A while back on YouTube Brewmaster Ben did a video on Do we need to prime homebrew?