Thank you - this worked (altho I had to use a GridTemplateColumn):
GridTemplateColumn productNameColumn = masterTable.GetColumnSafe("ProductName") as GridTemplateColumn;
This does break the 'onBatchEditCommand' as the item is removed from the 'oldValues/newValues' lists,
however I should be able to work round this with some extra code to pull the original values.
Thank you for your help