These guys have made and sold billion of these things for a long, long time, do you think they don't know what makes most beers skunk?
Newcastle is served in clear glass bottles because they use hop extract instead of fresh hops or hop pellets in their beer. The enzime that reacts with UV rays to "SKUNK" beer is NOT present in hop extract, so you can not skunk a Newcastle. Same thing with Miller High Life or pretty much any other beer served in a clear bottle.
You may not like the taste of Newcastle, it is very light, low alcohol, and super malty (high relative proportion of Crystal Malt in the recipe), but you did not drink one that was skunked. Old, maybe, but not skunked. Scientifically impossible. Do your own research if you don't believe me.