Why do you refuse to use any book written in the last half century?
Celtic Researchs is from 1804. Why is that more trustworthy to you than anything written in the 1990s or the 2000s?
From whom are the newer books getting their histories if not the ancient historians? I always go to the source, when possible. I don't want to know what someone thinks about what someone thinks about what someone thinks, etc ad nauseam. If I ever go to someplace like Wikipedia, I'm looking for the references, not their take on what the references have to say. It may be unusual to conclude for oneself, but if you're wrong you can always go back to the beginning, correct the conclusion, and thereby learn from the experience. Taking a fully-baked conclusion as fact dismisses the opportunity to learn a truth which may not have been apparent to the conclusion-writer.
And to be fair, I DID reference Whatmough and Sims-Williams... and will add Cunliffe:
"Avienus makes only one direct reference to the Celts when he mentions that beyond the tin-producing Oestrymnides was a land now occupied by the Celts, who took it from the Ligurians."--The Ancient Celts
And in the below I have shown what older authors said about the Saluvii/Salyees found in the Iberian/Ligurian Peninsula... to which I will add this, showing from where in the Iberian Peninsula came the Silurians, IMO:
"Selon Strabon III, 148, [Greek] était dans la région de Castulon; là se trouvaient les sources du Bétis et de l'Anas.1 C'était la base de la Sierra Morena.
A la suite du mons Silurus, le long de la côte, se dressait au Sud de Lorca un mons Argentarius Ilurconensis, où des mines d'argent étaient exploitées sous l'empire.2
Argentarius est la traduction latine du grec [] que portait le périple initial. Ce mot était lui-même la traduction, soit d'un terme indigène, soit d'un terme usité par d'autres navigateurs, qui pouvaient avoir été les initiateurs des Grecs dans cette région. Or, des Ligures paraissent y avoir été établis, car ils ont laissé la trace de leur présence dans la toponymie. Le fleuve Tartessus, c'est-à-dire, le Bétis ou le Guadalquivir, traversait au temps du Périple un Ligustinus Lacus.3
Il y aurait eu dans les environs une ville nommée [Greek, Ligustine],4 Les Ligures venaient d'être chassés du centre de la péninsule.5 On a tenté de les effacer de la carte historique de l'Espagne.6 La netteté des informations d'Avienus l'interdit, à mon avis; elles sont d'ailleurs confirmées par la présence, dans la toponymie ancienne delà péninsule, des éléments caractéristiques de la toponymie ligure.7 Je suis persuadé que les montagnes qui se font face portent le même nom en deux langues dont l'une serait le ligure. Mais en voici peutêtre la preuve."
1. Strabon, III, 148, D'Arbois de Jubainville. 0. 1., t. II, p. 210.
2. Revue Archéologique, 1907, I, p. 58.
3. Avienus, Ora maritima 62: sed insulam | Tartessus amnis ex Ligustino lacu | per aperta fusus undique adlapsu ligat.
4. Steph. [Λιγυστινη, Πολισ λιγυων της δυτιχης Ι.ηοιασ εγγθς και της Ταοτησσου πλησιον]; Pline III, 25.
5. Avienus, Ora maritima, 154, 196.
6. E. Philipon, Les Ibères, p. 58; Id., Les peuples primitifs de l'Europe
méridionale, passim. M. Philipon, qui dépossède les Ligures au profit des Ibères, a fait des Ibères qui sont des demi-Ligures et dont le langage ressemblerait de très près au ligure. {who dispossessed the Ligurians for the benefit of the Iberians, made Iberians who are demi-Ligurians and whose language would closely resemble Ligurian}
7. D'Arbois de Jubainville, 0. 1., p. 69 sqq. (noms en -asco, -osco), p. 117 sqq. Schulten, Numantia, p. 61 sqq.
Mons Silurus is the Sierra Mountains lying just south of Lake Ligure in what Strabo called the Ligurian Peninsula.
The so-called metal "Ages" happened at different times in different places. The Druids may have been spoken of by that name during the time of the Roman Empire, but that doesn't mean they "originated" in that time.
If anything, the late-coming Celtic-speaking people are earlier "practitioners of cultural appropriation".
"Bertrand and Reinach both maintain the pre-Celtic origin of Druidism."
--Wright, Druidism the Ancient Faith of Britain
"so we must pass on to the non-Celtic natives, who had another religion, namely, druidism, which may be surmised to have had its origin among them."--Rhys, Celtic Britain, p.69
"Professor Rhys goes so far as to refer Druidism to the Silurian race, because Caesar mentions Britain as the birthplace of that cultus, and it is of a character which he considers non-Aryan. It is almost certain that second-sight and other ecstatic moods must be referred to the pre-Celtic races."--MacBain, Celtic Mythology and Religion
"The monuments we call Druidical, must be appropriated, exclusively, to the Aborigines of the midland, and western divisions. They are found in such corners, and fastnesses, as have, in all ages, and countries, been the last retreat of the conquered, and the last that are occupied by the victorious."--Davies, Celtic Researches
"The Celtic invaders of Britain did not create Druidism, and, neolithic or not, it was at all events pre-Celtic."--Holmes, Caesar's Conquest
Therefore, who are the "non-Celtic natives" of Britain?
"Strabo reports of Posidonius ... 'The Cassiterides are ten in number, and lie near each other in the ocean, towards the north from the haven of the Artabri: one of them is desert, but the others are inhabited by men in black cloaks, clad in tunics reaching to the feet, and girt about the breast; walking with staves, and bearded like goats. They subsist by their cattle, leading for the most part a wandering life. And having metals of tin and lead, these and skins they barter with the merchants for earthenware and salt, and brazen vessels.' ...
Solinus ... states that 'a stormy channel separates the coast which the Damnonii occupy from the island Silura, whose inhabitants preserve the ancient manners, reject money, barter merchandise, value what they require by exchange rather than by price, worship the gods, and both men and women profess a knowledge of the future.'"
--Skene, Celtic Scotland,v1
"The wide extension of the Ligues westward is in agreement with the language of Eratosthenes. According to Strabo (2. i. 40, p. 92) this old geographer taught that there were three forelands projecting from the north—the Peloponnesian, the Italian, and the Ligurian—between the first and second of which lay the Adriatic, and between the second and third the Tyrrhenian Sea. When we remember the high reputation and the real merits of Eratosthenes, it is astonishing how little attention has been drawn to the fact that he calls the Spanish peninsula the Ligurian."
--Guest, Origines Celtae
"The swarthy complexion and curled hair of the Silures, together with their situation opposite to Spain, render it probable that a colony of the ancient Iberi possessed themselves of that territory."
--Tacitus, Agricola
These are the indigenous people of Western Europe who had the stone circles and nemetons, and the Druids. The Celtic language evolved from the Ligurian, and IMO, is proven by Whatmough and Sims-Williams.