As you know RJ there is no sense to be made of this. It is, as you stated, simply a marketing ploy.
To be British is akin to being American. It is called the British Isles which at one time included Ireland, and today includes Scotland, Wales the surrounding islands, like the isle of Man, Western Isles, Orkney, Shetlands, Isle of Man. It is a hodgepodge of haplogroups.
No one knows who the original Brits were, but the "Cheddar man", from DNA analysis, indicates that he had dark skin, brown eyes, and black hair. Then came successive waves of migrating tribes, then the Romans, who seem not to have much if any trace of their DNA, and that goes for their auxillaries, like the Syrian sling throwers, the Sarmatian cavalry, then the Angles, Saxons and Jutes, who left lots of their DNA, mostly in the south, midlands and along the east coast, finally then the DNA's who occupied the Angleland north of Watling Street, then the Norse who raided into and temporarily ruled the northern counties, then called Northumbria, and finally the Normans.
The Norman presence most strongly felt in the south and midland counties. But the Normans themselves were Frankicized Vikings, of Danish/Norwegian origin and mixed DNA.
Williams right flank at Hastings were Frankish/Frisian/German/Polish/ and even Moorish mercenaries. His left flank were Bretons, descendants of Brits who had either migrated before the Saxon invasion or fled to France in the wake of the Saxon invasion.
Scottish DNA (which is also British) is largely Pictish with an admixture of Norse. English DNA is Brythonnic, Celtic, Saxon, Angle, Jute, Dane and Norse.
But there really isn't such a thing as Norse or Dane DNA, because they run the gamut from haplogroup E to I2, I1, R1a, R1b.
There is one haplogroup that is decidely Norse, or rather New Norse, aka Norse Viking. Viking medieval English wicking, is not a people, more of an epithet/job description it meant sea raider or pirate.
Like British, there is no such thing as Viking DNA. Vikings were a hodgepodge of mostly Germanic Peoples, but represented within them were haplogroups of other peoples, like Slavs and even Arabs.
Vikings were Danish, Frisian, even Celtic,and then there were the Pictish Vikings from Orkney
But there was a particular "flavor" of Viking, whose ancestor was born north of Oslo: R-YP386 (R1a1a1b1a3b1b) and probably it's parent clade of R-Z84 This clade has been identified as new Norse.
The result is that there really is no such thing as British DNA. I would guess that it's largest component is the Western Atlantic Modal (R1b1..and it's subclades), but there is Saxon, Danish whose major component is I1.
I think that it is an error and misleading to classify any DNA or haplogroup by modern political boundaries. The species is migratory and warring. Absorbing and obliterating peoples as it spreads across the planet. Our species is particularly good at wiping out other species, (including homo sapiens) making them extinct or a virtual genocide.
Take Haplotype E, for instance. It is found in greatest numbers in Africa, but Africa is simply a continent with a wide range of habitats and peoples. Home to caucasoids and negroids alike and all ranges and admixtures between.
You find E1b's in western Africa, Norhtern Africa and in the Balkans, not to mention Corsica and Sardinia. Napoleon was E1b.
Haplogroup R1a ranges, in small numbers, in Britain, Scandanavia, Germany, Italy to (larger numbers) the Indian Subcontinent.
R1b, is the dominant paternal haplogroup in Europe google Distribution of R1b in Europe
Compare that to the sparse representation of Distribution of R1a haplogroup in Europe.
No doubt that there are localized or relatively localized subclades that can definitely said to be ethnic in origin, but to determine that requires a mass testing of Big Y for SNP's (Single Nucleotide Polymorphisms)
But ancestry.com and 23andme and FTDNA's Family Finder bases their ethnicity guesstimates on autosomal DNA, and auDNA has a tendency to be diluted and segements disappearing within as little as 6 or 7 generations. So in reality autosomal DNA is not even a reliable estimate.
Better yet is YDNA, and mtDNA. mtDNA mutates so slowly is passed down via the female line, males don't pass on mtDNA to sons, only to daughters, and mtDNA can be traced backwards tens of thousands of years, the same with YDNA.
Autosomal DNA, given that it washes or is diluted after at least 7 generations, what we are left with are self reported ethnic ancestries of those persons who claim this or that ancestry. And such claims are mostly made out of ignorance, at least for Americans of majority European ancestry.
