Hi Peter, your need for more accurate date for Alan de Elsfield is shown in the following book as brother of Richard de Elsfield from which see see when he was appointed the Constable of Bordeaux. In Great Britain. Public Record Office, H. C. Maxwell Lyte (Sir.) Kraus Reprint, 1971 - Great Britain for the years (1321-1324), Alan de Elsfield is shown in the index as appearing on pages, 136,318,and 319, and it is followed by "Richard his brother" who also appears on page 318. that gives you the same time period for both brothers. Source: Richard of Elsfield as Constable of Bordeaux, 1318-20 Esme Pole Stuart and Hilda Johnstone The English Historical Review Vol. 52, No. 205 (Jan., 1937), pp. 23-38 link to an excerpt: copy and paste! https://academic.oup.com/ehr/article-abstract/LII/CCV/23/467434/Richard-of-Elsfield-as-Constable-of-Bordeaux-1318?redirectedFrom=fulltext Richard of Elsfeld, brother of Alan of Elsfeild served as the Constable of Boreaux, Gascony from 1318-1320. According to the book his time here went very badly. Robert