It’s handy that I could lay my hands on the answer. For those of you who are interested, section 80 of the BFDA provides:
“1. Bank holidays
3. Her Majesty may from time to time by proclamation appoint a special day to be, either throughout the United Kingdom or in any place or locality in the United Kingdom, a bank holiday under this Act.”
This means that any day of the year can be a public holiday, provided the Queen proclaims it. This year, that was 1 January and 3 May in England, Wales and Northern Ireland (see the 11 June 2009 edition of the London Gazette).
I for one would appreciate a few more!