great stuff.

the CELL("Filename",INDIRECT("A1")) works perfectly to return the
reference of the calling cell.

the latter assumption is correct - so defining the name as above, then
in a cell putting =London!MonthSales works but
=INDIRECT("London!MonthSales") does not.

I tried reverting to the INDEX style syntax (great tip - thanks) but
unfortunately this doesn't work either - still getting a #REF! error.
What is even more strange is that putting
=CELL("address",London!MonthSales) returns the correct cell reference
as you say....?

There must be something in the definition of the names that can't be
resolved when the reference uses INDIRECT.

I tried putting =INDIRECT("WorksheetName") in a cell and it returns the
#REF! error - could this be the problem?

NB. WorksheetName =RIGHT(CELL("filename",INDIRECT("A1")),
LEN(CELL("filename",INDIRECT("A1")))-
FIND("]",CELL("filename",INDIRECT("A1"))))

thanks
Rob