Crossmatching of northern and southern Irish tree-ring chronologies confirms that Ireland can be treated as a single tree-ring area; the reference curve now covers the period 12 B.C. to the present (with a 30-year gap ca 900 A. D. A dozen Irish horizontal mills have been dated, many to the period 780-880 A. D. The Tamworth (Staffs) mill has yielded a tree-ring date of ca 855 A.D. (rather later than the Offan date suggested by ¹⁴C), and the vertical mill at Old Windsor one of late 7th century. -- AATA