Putting it All Together

The TMRCA of my uncle and the Viking skeleton from Orkney is 900, give or take. This date coupled with the fact that the Viking era in Britain lasted from 800-1150 implies that the first British member of my Livingston line was someone of Norse Viking—possibly Danish—lineage who arrived in Britain some time after the year 800. If the line is that of Leving, then Leving was the descendant of Norse Vikings, and there is no genetic relationship between Clan Livingstone, who were well established in Scotland centuries before the Viking era began.

And we can be more precise about the origin of the line. The FTDNA analysis at the time of writing gives 11 Livingston matches. 6 of these are Scandinavian, 5 are British. The Brits in order of closeness are named Toothill, Musgrave, Blance, Aimers, and Farrar. Blance's name is unique to Shetland, which together with Orkney, was annexed by the King of Norway in 878. As the following post on a Norway Heritage site makes clear, Blance is a Norseman:   

Hi  I am researching my family and have just found out that on my paternal line we come from Norse Vikings in Norway. I was wondering if there would be any of my ancestors descendants still living in Norway and/or if anyone could help me with my genealogy in Norway?  My surname is Blanch - it was in Shetland Blance and previously Blanx or Blanj. We have undertaken a DNA study and the administrator of the study thinks the name may have originally been Bljanson /Bljansen or something like that.

We can learn at lot then from the Brits, Toothill, Musgrave, Aimers, and Farrar. Like the great majority of us, they can't trace their paternal lines back further than a century or 3, but their names are anglicisations of the Old Norman names, Totelles, Musegros, Amaury, and Ferrers. "Toothill" is spelled in various ways: Tuttle, Tuttell, Tathill, Toothill, Tolehill, Toteles, Touthill, Tutoil, Taythill and Tothyll. According to one account, it derives from the Old Norse þorkell, a contracted form of a name composed of the elements Þórr (Thor) and ketill (cauldron).The Toothills and their namesakes are proud of the fact that the first name on the Battle Abbey Roll is "Toteles" or "Totelles": 

Totelles : Totel in Duchesne's copy. This may be a Norman name, but it is suspiciously like Tothill in England...

"Musegros" also appears on the Battle Abbey Roll, where it is explicitly stated that "Musgrave" is the modernised form:

 Musegros : from Mucegros, near Ecouen. This name, so largely represented in England, is repeated further on in its modernized form of Musgrave...

"Ferrers" appears on the Roll, and the Ferrers' were big players in post-conquest Britain:

Ferrers : from Ferrieres-St.-Hilaire, near Bernai, in Normandy, sometimes called St. Hilaire de Ferrieres.

"Farrar" is an alternative spelling:
The principal contemporary alternate spelling [of Farrar] is Ferrar. Other versions, including archaic ones, are Farrars, Ferrars, de Ferrars, Ferrars de Groby, de Ferriers, de Ferrières and the oldest known form, de Ferrières-Saint-Hilaire.

The latest Big-Y match is to a Willam L Aimers. "Aimers" was originally derived from the Old French 'amauri' meaning 'work-rule'. The name D'Amery or Amoury was first found in Tours, Normandy, it appears on the Battle Abbey Rolls, and was brought to Britain by the Normans.   

Running through my uncle's 111 marker STR matches, we find in addition to a pair of Livingstons, 2 Scandinavians, Tootthill and Musgrave, a Burke. Burke comes from de Burgh, and from Robert de Burgh, the Earl of Moreton in Normandy who fought at Hastings, and was created Earl of Cornwall. Yet another British Livingston relative on the Battle Abbey Roll.

There is a very clear pattern emerging here: the Livingstons and their non-Scandinavian Y-DNA relatives have names that are anglisations of Norman names that appear on the Battle Abbey Roll, to wit: Leving (Loveyn, Lieuvin), Toothill (Toteles), Musgrave (Musegros), Aimers (Amaury), Farrar (Ferrers), Burke (Burgh). The first British member of my uncle's line, it can be theorised from the DNA evidence, together with the historical and linguistic evidence, was someone of Norse Viking ancestry who came to Britain from Normandy during or following the Norman Invasion of 1066. And there is more than enough evidence here to theorise that this ancestor was Leving or -what is more likely- Leving's father. 

To make progress towards a proof of this theory, and the final answer to the questions above, we need more Big-Y test results, and in particular we need Big-Y test results for lines with reliable paper trails leading back to the Livingstons of Callendar. No doubt there are many other candidates, but the only such person presently in the public eye is ex-senator Bob Livingston (pictured below):

Because he has an impeccable paper trail leading back to Rev. John Livingston, who is a known descendant of the Livingstons of Callendar, Bob could single handedly establish the Y-DNA signature of the lowland Livingstons once and for all. At very least, his test results would carry a weight that other results do not.