I did find one little bug...

If I apply this query to a certain range of data I get the entire data set rather than the summary. However, if I comment...

:Wow: :Wow: Double wow! That took all of 2 seconds! Now, some caching into memory may have been involved so I reran the first query and it took 3:46 so...

:Wow: Wow! That is absolutely amazing. It does exactly what I wanted and although it takes a while on a production database (3:47 over a base table of 137,003 rows)...