A good way of handling dates that may be in UK or US format is to make
the cells DD MMM YYYY format (or MMM DD YYYY as you see fit) which puts
the month name into alpha format. Another thought I should mention is
that I have many programs which extract dates from mainframe systems,
and I ALWAYS pull in the dateserial of the day, month and year part of
the date rather than relying on Excel to interpret the input. When
items are input manually, then have the cell pre-formatted as a date,
and also use data validation to ensure that they PUT dates - many users
think that 01.01.01 is OK as a date!