Possible Day of Mourning - implications?

Over in 'letting off steam', people are discussing the rights or wrongs of whether we should have a Day of Mourning for the Pope's death.

If a day of mourning is declared for Friday, do I have to give my employees the day off? If I insist they work, do I have to pay overtime etc? Will it become a Public Holiday/Bank Holiday etc?

What are the implications for business owners?

Where I work, the DOM for 9/11 was treated as a public holiday.

Where I worked at the time, I was told I could take the day off, but that I would have to take the following day off also, and the following day, and the following day....

God I hated those people.

I am closing my office at 12 noon to 2pm as a mark of respect to the Pope and also to allow the staff go to mass if they so wish.