Excellent! Works a treat. Many thanks.
As a point of interest, there are four other columns with similar sums. Three use autosum and have (or rather 'had') the same issue. The fourth column looks across the 'totals' rows and adds them, something like =A11+B11+C11, and this one updates correctly to =A12+B12+C12 when a row is inserted. I shall look for a setting, but probably not too hard as your answer solves the problem.
Thanks again!