In the archaeological record for Bronze Age Europe, one of the best attested forms of musical instrument is the horn, generally considered to be used primarily as a battle instrument, although throughout history, they have also been associated with religious ceremony, and with hunting. Unsurprisingly, perhaps, the early Classical writers tend to focus on the idea of battle-horns, as in Polybius' report of the Battle of Telemon in 225BC between the Romans and the Celts, describing the "dreadful din" of the Celts' horns:
for there were innumerable hornblowers and trumpeters and, as the whole army were shouting their war-cries at the same time, there was such a tumult of sound that it seemed that not only the trumpeters and the soldiers but all the country round had got a voice and caught up the cry[1]
No doubt, the most famous form of ancient Celtic horn (or trumpet) was the carnyx. However, more common types of prehistoric horn have also been found in Scotland, and although none have been found in Lothian to date, it is likely that horns of these types would also have been used here, as they were throughout much of the prehistoric Celtic world.
Unfortunately, few ancient horns have survived in Scotland, and none, so far as is known, specifically from Lothian. However, one horn exists from the South-west, and this horn is often claimed as the earliest surviving musical instrument of any kind from Scotland, being dated at almost 3000 years old. This small yet revealing fragment was found beside a medieval motte site at Innermessan near Stranraer, in modern Dumfries and Galloway (click here for a location map provided by StreetMap).

The Innermessan Horn Fragment (Munro, 1899)
Organologically, we can say that this was a side-blown instrument (rather than end-blown), since the raised rim of the mouth aperture and its placing on the side of the body is clearly evident (right, on the above sketch). Furthermore, we can say that it was a curved instrument, most likely in the shape of a bull's horn, giving it the overall appearance of a medieval hunting-horn of the more familiar kind. This, and the deducible size and style of the instrument, relates it to some of the more complete finds from Ireland, some of which can be seen at Prehistoric Music Ireland.
The Innermessan Horn dates from the C8th BC (the Bronze Age) and as such, we can say little about its ethnic provenance. However, according to the Greek cartographer, Ptolemy, writing around 1000 years later in the C2nd AD, that area was by then occupied by the Novantae tribe. Of course, the Novantae lands eventually became, in the early historical period, part of the border area between the ancient Brythonic kingdoms of Strathclyde and Rheged, the Western sister-cultures of Lothian's own Gododdin. It is thus more than feasible to assume the use of similar horns within ancient Lothian itself, during what we might call the proto-Gododdin era. However, horns of this type seem to have been used throughout a very lengthy period indeed, across Celtic Europe and beyond, and the Gododdin per se would likely have made use of instruments very much like it.
Another early horn exists from the South-west, found in the C17th at Coilsfield near Tarbolton in Ayrshire, and although its precise find-location has been lost, there is a prehistoric cairn in the immediate area, which may be indicative (click here for a rough location map from StreetMap). Indeed, local tradition claims this cairn to have been the burial-mound of none other than Coel Hen (pron. "coil hain"), the early historical king of the area and progenitor of many of the powerful Celtic kings of the old Brythonic North (Y Gogledd), with many dynastic links to the Gododdin nobility in Lothian. To this day, the modern district of Kyle in this area is said to be named after Coel, and presumably his name lies at the root of the placename of the findsite - Coilsfield - which in Brythonic/Old Welsh would perhaps have been Maes Coel. Coel is also immortalised in several of Robert Burns' poems as "King Coilus", reigning over "Coila". Most famously, though, we have Coel represented in the modern nursery rhyme Old King Cole who, if the rhyme is correct, was, appropriately enough, a "merry old soul" who was rather partial to music!

The Caprington Horn (Munro, 1899)
However, the precise dating of this instrument has been a matter of some controversy, with theories ranging between the late Bronze Age[2] right up to even the medieval period. If it is indeed ancient rather than medieval, then it represents the earliest playable musical instrument yet found in Scotland. Certainly, it is mainly of cast bronze, although an area of it has been repaired at some point with brass. Nonetheless, aspects of its style suggest close parallels with other Bronze Age finds throughout Europe.[3] Other than that, about all we can say is that if it is indeed from the late Bronze Age or even the early historical period of Coel Hen and his ilk, then like the Innermessan Horn, it would certainly have not seemed unfamiliar to the Gododdin of ancient Lothian.
more to follow...
footnotes
[1] Polybius, History 29. 5-9.
[2] J.G. Callander, "Scottish Bronze Age hoards", in Proceedings of the Society of Antiquities of Scotland, 57, 1922-3, p.160.
[3] John Purser, Scotland's Music (Edinburgh: Mainstream, 1992), pp.26-27.