I agree with cdiebolt. While there was no such date in England's dating system at the time, it's a perfectly valid date in the Gregorian calendar, and corresponds to various dates in various countries' national systems.

So the function DOES do what I expected, hence it runs perfectly. "Perfect" is in the of the beholder, so not a word to be used in a specification - unless itself specified for the occasion. Please make the possible answers unambiguous in future - and scope the conditions precisely too.

I wonder if anyone has created a nation-sensitive historic date system in which [font="Courier New"]Date('1752-09-02') + 1[/font] would give the correct result depending on country. e.g. [font="Courier New"]'1752-09-13'[/font] in England (and I think the rest of the UK), and [font="Courier New"]'1752-09-03'[/font] in The Netherlands? It would be hard to do; you couldn't use ISO country codes to indicate locale, as some no longer exist and others (e.g. Belgium) were parts of multiple other countries at the time.