Turnbull's 2009 Coals from Newcastle was not accessible in digitized form; the Newcastle HER's page-specific citations to it support the 'Heaton Banks' name and an undated pit map, not unambiguously the 1745 closure sentence

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[unverified-quote — needs direct read]: this note's claim concerns a citing source's own citation apparatus, not the underlying historical fact, and clears the sourcing floor for that (Tier 3–4 acceptable for documentary/citation-structure claims per sources.md); the underlying 1745 date itself remains [unverified-quant — needs primary] pending a direct read of Turnbull.

Repeated searches this session (general web search, Google Books, Internet Archive full-text search, UK antiquarian/secondhand-book listings) found no digitized copy, preview, or excerpt of Les Turnbull's 2009 Coals from Newcastle: An Introduction to the Northumberland and Durham Coalfield (Chapman Research Publishing, 142pp). It survives only as an out-of-print physical paperback. On Newcastle's Historic Environment Record page "Heaton Colliery to Wincomblee Waggonway" (HER 15338), two sentences carry explicit, page-specific citations to this book: one for the "Heaton Banks" name and an undated pit map ("Turnbull 2009, 34"). The sentence stating the 1745 closure — "The colliery closed in 1745, flooded out and superseded by Longbenton West Colliery" — immediately follows a different citation, to Hope-Dodds 1930 p. 436, for the waggonway route on a separate 1745 estate map, and carries no citation marker of its own.

The HER page therefore does not unambiguously say which of its two named primaries the closure date comes from. Given that a direct read of Hope-Dodds's own volume found no such date and a narrative arguing the other way (see claim-hope-dodds-1930-heaton-chapter-contradicts-1745-closure-date), Turnbull 2009 pp. 32-34 is the more likely source of the 1745 figure specifically — but this remains unconfirmed, since the book itself could not be read. See question-verify-heaton-banks-colliery-1745-closure-date and entity-les-turnbull.