[Agrippa]

Originally Posted by Mynydd

You are missing a few details. One is that the environment here calls for similar patterns of adaptation.

Sure.

Another, that it wouldn't explain the Mediterranoid/Atlantoid phenotype in elements in places like The Lowlands.

The way of life and selective pressures which go much beyond the climate alone can be as or even more important especially inside of a related spectrum and with not too extreme climatic differences.

And last, that it is the Nordid and Northern Cromagnoid input that give the different general look in the Lowlands.

Under the early Neolithics we find Atlantomediterranid or Atlanto-Pontid like variants, like you want, too. If you put a wider Mediterranid variation under selective pressures of different kinds, you get different results out of this process. So if there are a lot of more mobile and warlike herders in smaller and medium sized groups its different from sedentary, peaceful tillers living from crops primarily in greater groups which suffer from plagues and bad hygienic conditions.

The climate might in general lead to bigger, taller variants in the relatively colder areas, but even in a warmer environment the same variants - just darker - can come up if they are need and their advantages are more striking than their small, climate-caused, disadvantages. Which is the case especially if we have a high level individual and especially group selection.

And, since the Neolithic impact seems to be fairly more significant in Germany, perhaps it would explain those though to be Mediterranoids/Atlantoids? Scratch a German.. ?

The Neolithic influence might have had an significant impact on Nordoids as well as Mediterranids in my opinion, though the original form was simply closer to a modern Mediterranid than Nordid with a stronger input in the first.
The populations of Europe before the Ice Age were not the same as they were afterwards, even before the Neolithic transition - at least racially. There might have been a large genetic continuity, but the racial spectrum and trait-combination percentages changed.
This can be caused by more Southern input or not, depending on the exact region and type in question, but in the end this is secondary if the end result is so similar.