Thanks for the follow-up Rory, but I've just thought of a potential problem. Presumably all simple cell references like B12, which were OK for a macro in the same workbook it was intended to be run, would have to be expanded to explicitly show the workbook and worksheet?

If so, is there an intuitive edit that will always work, such as changing it to something like WorkbookName.Worksheet.B12?

Maybe I'll post separately about this more general question.