The Willington Waggonway excavation report measures a 1785-dated siding at a full 4 ft 8½ in gauge, stated as the same as the main line

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Describing the excavated wash-pond siding at the Willington Waggonway (former Neptune Shipyard site, Wallsend), Richard Carlton and Alan Williams's peer-reviewed excavation report gives the rails' spacing as "about 1.44 m apart (4 feet 8 ½ inches)," measured from the inside faces of the rails, and states that this siding runs at the same gauge as the main line. The report ties construction of the site to the Bigges Main pit, "sunk in 1785." This is a direct Tier-1 measurement — the excavating archaeologists' own description of their own excavated remains — and is the most direct primary-source support located so far for the claim, previously resting only on a museum blog's gloss in claim-willington-waggonway-1785-excavation-claims-full-gauge-predates-stephenson, that the full 4 ft 8½ in figure, not merely the base 4 ft 8 in, existed physically in the ground decades before George Stephenson's career. The report's own Conclusions separately describe the international "standard" gauge as "ultimately defined as 4' 8½" or 1.435 m," using the same full figure once more, in a passage about the site's significance rather than what was directly measured.

This does not settle the question cleanly: the same report's Conclusions elsewhere describe the identical main line as "four foot eight inch" gauge, with no half-inch — see claim-willington-report-main-line-stated-four-foot-eight-inch-no-half-inch. The two figures sit side by side, unreconciled, in the same short document.