Cornelius Walford's own three-period taxonomy of English life-assurance history places the Amicable Society's 1706 founding in the 'Speculative or Transitional Period,' and credits Price's Northampton-table work with ending it

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In the "Preliminary Survey" opening his serialized 1884–85 prize essay, Cornelius Walford divides the history of English life assurance into three named phases: "(1). The Experimental Period; (2). The Speculative or Transitional Period; (3). The Period of Scientific Exactitude." The boundary he draws between the second and third periods is explicitly about data, not custom. Describing the Mutual Contribution and Annuity Societies of the early eighteenth century — the class of institution the Amicable Society (1706) belonged to — Walford writes that "in the absence of available scientific data on which to base their operations, they proved most delusive. Reversionary interests could not be accurately valued, and hence were the subject of speculation only."

Walford places the Amicable's own founding inside this second, "Speculative or Transitional" period: introducing it, he writes that "the movement of 1706 was intended to be in the direction of permanence." He then dates the event that closes the period to a named person and year: "Attempts were therefore made during the next Century to construct other tables based upon English observations — especially upon those of London; and afterwards upon those of the central Town of Northampton. From the accomplishment of this last result by Dr. Price in 1769, dates what may be termed a general adoption of Life Assurance for its best and noblest purposes." This is Richard Price's Northampton table, the same work anchoring claim-price-northampton-table-standard-actuarial-reference-century.

The taxonomy is Walford's own explicit historiographical framework — he names and numbers the periods himself, and states outright which person and year he credits with ending the second one — not an inference drawn by a later reader. It is the periodizing scaffold several of the vault's other actuarial-history claims (Halley, Dodson, Price, Galloway) implicitly sit inside without any of them naming it directly.