I've setup a very specific function and it works well but I'd like to make the parameters optional but I can't get a handle on the regex bit:
/whats-on/2012/01/25 I'll show all events on this date.
/whats-on/2012/01 goes to 404 but I'd like the parameter to be optional so I can show all January dates and the same for
/whats-on/2012 all dates in year 2012
Any help will gratefully received - thanks