Bailey's Irish Cream
A major Kashrus concern is the general ignorance in dealing with kosher liquor. A lot of uninformed people assume that anything alcoholic is acceptable, which is certainly not the case. Of note are alcoholic beverages that are flavored (ie. flavored vodka). Because not all companies reveal the source of the their flavorings, the general rule to follow is that if it is flavored, it either needs a hechsher or a kashrus organization vouging for it. As such, when reading lists of acceptable liquors/liquers from different organizations, most will note that flavored liquors/liquers need certification; if not, they fall under the category of "not recommended".
One such drink is Bailey's Irish Cream.
Interestingly, when we were in Israel, both places we were for Shabbos had Bailey's. I assumed they were not aware of its problematic status and I, therefore, refrained from consuming them. After thinking about it though, I decided to look into the matter a little more. One of my friends that I stayed by with for Shabbos had heard that it was acceptable in London; but that's all he knew. I spoke with the London Beis Din Kashrus organization, which confirmed that it is, indeed, OK to drink (which I later saw on their website).
But, just because something is kosher in one country doesn't necessarily mean it is kosher in all places. Often times, major companies have more than one production/bottling plants. Obviously, if the different plans are altering the ingredients, even slightly, it would be problematic. But assuming the ingredients are the same, it still does not guarantee that the product is OK. The plants in different countries would each need to be checked by a mashgiach or kashrus agency, as there are other kashrus issues aside from the ingredients themselves.
I then called Diageo, who owns Bailey's Irish Cream, for clarification. They informed me that all production happens in one place, in Dublin, Ireland. Furthermore, the same machines used to make the UK Bailey's are the exact machines used to product the US Bailey's. She told me if I bought a bottle in the US it would be the exact same thing, from the same machines, as if I bought a bottle from the UK.
However, the Star-K, CRC, and Montreal Kashrus organizations all list them as not recommended. I realized, however, that this is not because of their worry about flavorings; rather, because of the fact that they do not certify products that are not Chalav Yisroel.
I, of course, cannot speak for your local rabbinic authority. All I can do is report that the product sold in the UK, which is 100% kosher, is the same product, from the same machinery, as the contents of a bottle that you can find in your local liquor store here in America. Cheers!