May have answered my own question...
excelramblings.blogspot .co.uk/2013/03/strings-and-garbage-collector-in-vba.html
msdn.microsoft .com/en-us/library/ms182272(v=vs.80).aspx
(Do not concatenate strings inside loops)
(Added a space inside each url otherwise wouldn't let me post)
EDIT...
I needed to create a crosstab style report with varying columns and conditional formatting. I know there are some workarounds to do this in Access, but after a lot of frustration I ended up exporting the data to a html file instead, where some simple javascript displayed it and formatted it.
In...