wrote...
....
So far I have: {=SUM(((Presentations)=VALUE("1 Jan 2009"))*
((Presentations)<=VALUE("31 Jan 2009")))} . . . I
need to add to this to find "who returned" in the next colum taking
into mind that I cannot apply the formula to the whole of the next
colum as the clients date of return does vary. . . .

If Presentations refers to a cell in one column and Returns refers to
the cell one column to the right of the Presentations cell, try

=IF(AND(TEXT(Presentations,"yyyymmm")="2009Jan",CO UNT
(Returns)),Returns,"")

On the other hand, it looks like your original formula is an array
formula, so Presentations would seem to be a multiple cell range. If
so, it's unclear what exactly you want. If you want the first date of
return after Jan 2009 for those with presentations in Jan 2009, try
the array formula

=MIN(IF((TEXT(Presentations,"yyyymmm")="2009Jan")
*(ReturnsDATE(2009,1,31)),Returns))

If you want something else, please describe in greater detail ALL the
data fields involved, what their rough size/shape is (single or
multiple column, single or multiple row), and how the result should be
determined from the data.