I am intrigued by this repartee! Are you saying that since there are Bell Beaker examples in both P312 and in U106 in Scotland that these Germanic haplogroups are really both Celtic? I think that would be difficult to sustain given the extant evidence to the contrary. However I do feel that S21 in Scotland is more likely to be intra-UK migration from the South ( whose S21 may have been derived from Danish Vikings as well as Anglo-Saxons) that due to Norse Viking invasions