We have little detailed land-assessment evidence for Iona and what we do have is ambiguous. In 1509 (ER XIII p 214) and 1561 (CRA p 1) Iona was given as a £20 or 30m land. In 1587-8 (CRA p 161 ff) the former rent for Iona is given as 30m but the land value is not specified. In 1672 (HP I p 259) Iona is given as 15m (£10). In 1679 (HP I p 315) and 1694 (Clan Campbell I p 42) it is given as £10 (15m). In 1674 (HP I p 283) there is reference to 2d of Iona. In 1751 (Argyll Valuation Roll p 70) the east end of Iona is given as 5d and the west end as 6½d.
What are we to make of this conflicting data? There seems to have been a memory of Iona as a £20 or 30m land but I suspect this may have included properties other than Iona itself. However, since so many of the likely candidates also appear in the 1509 Exchequer Rolls it is difficult to know what these properties could be. In the late seventeenth-century rentals Iona is only rated at 15m which was half its previous value. In 1751 it appears as 11½d. Now 11½d at 1d:1¼m would be 14⅜m. (12d would be 15m). The pennyland evidence from 1751 is therefore consistent with the merkland evidence from 1672-1694. The problem is that one would expect Iona to have an ounceland to merkland ratio similar to that of its property in the Ross of Mull which was 1oz:10m or 1d:½m. As it is, it seems to share its ratio of 1d:1¼m with all of Mull except the Ross! This leaves me in a quandary as to the true situation in Iona. In fact I wonder if the pennyland valuation might be late and retrospective – if, for instance, Iona was given a notional value of 12d on the basis that it was thought to be 15m and in most of Mull 15m was the equivalent of 12d.
I have left Iona with a valuation of £20 or 30m on the grounds that this is the earliest. I think this should be viewed as 3 ouncelands (or davachs) like the Ross of Mull. I do not know if the Norse ever divided it into pennylands.