A tartan the earliest exact record of which (in the Key Pattern Book, 1819, of William Wilson & Son of Bannockburn) calls it "No. 64 or Abercromby", probably named after war hero Gen. Sir Ralph Abercromby. It is not one of the tartans conventionally used by Clan Abercromby/Abercrombie today. It is also probably (not certainly) the tartan used by Col. Robert Abercrombie or Abercromby's 75th (Highland) Regiment of Foot, raised 1787, later 75th (Stirlingshire) Regiment, later just 75th Regiment, before being amalgamated with 92nd (Gordon Highlanders) to form the new Childers Reforms version of the Gordon Highlanders in 1881. Source: Eslea MacDonald, Peter; The 1819 Key Pattern Book: One Hundred Original Tartans, 2012, p. 20.

The pattern with minor variations became many other tartans: "No. 2/64 or Abercrombie", AKA "Abercrombie with Yellow", using yellow instead of white; "No. 120", with red instead of black over-check on the purple; "Graham of Montrose" with blue instead of purple (though there are two other tartans by that name); and "Campbell of Breadalbane" with blue and yellow instead of purple and white.

This image is not just full-sett, and cannot tile horizontally or vertically; it is a centred zoom-out, for comparison to other tartans given the same treatment.

This is a usual, mirroring tartan. Scottish Register of Tartans does not have this sett, just several of the derived variants. I got the thread count from the book by Elsea MacDonald of Scottish Tartans Authority, and like most Wilsons patterns, it existed in a number of slight variants to account for different looms and qualities of cloth; I picked a "middle" option in proportions, that doesn't have any odd numbers in it. Thread count (in "/" notation): /B4 P24 B24 G24 W4 G24 B24/ (or in boldfacing notation: B4 P24 B24 G24 W4 G24 B24). If you prefer half-count-at-the-pivots (how Wilsons and Eslea MacDonald published it): B/2 P24 B24 G24 W4 G24 B/12. I adjusted the purple a little to not be too garish, and because sources indicate that the purple used in the period was blue-leaning compared to today's modern purple. Correction: SRT does have this sett, twice, but in one case the purple is much too red [1], and in the other case too dark [2], so the STA version is better anyway.