Since the vernacular wills themselves provide little insight into the process which produced them, any attempt to reconstruct that process must draw on other contemporary documents as well as narrative sources. One text is particularly valuable: the account in the twelfth-century Liber Eliensis of a sequence of post obitum dispositions made by a certain Siferth of Downham (Cambs.). Bishop Æthelwold's accumulation of land at Downham was not without incident, as in the case of many of Æthelwold's land deals; this appears to have prompted the compiler of the earlier Libellus, on which the chronicle account is based, to include a considerable amount of circumstantial detail for the transactions in support of Ely's title to the land, including, incidentally, Siferth's will-making.

The oral aspect of the will-making process is well demonstrated in the account of Siferth's declaration of two post obitum gifts at Ely, made on separate occasions, with considerable emphasis placed on the oral declaration before witnesses at every stage in these proceedings. His first declaration, which took place between 975 and 978, was made before particularly distinguished company: