XL Formula
If anyone wants to know I have devolped the following formula which seems to do the job.
=CHOOSE(ROW(),"Jan","Feb","Mar","Apr","May","Jun", "Jul","Aug","Sep","Oct","Nov","Dec")&" "&SUMPRODUCT(--(MONTH(($A$1:$A$30))=ROW()))
This first bit is for displaying the month in short in the first 12 rows only.
Rgds