"Chris has answered questions on this theme ad nauseam".
Yes, I seem to remember one or two (hundred) posts on this topic ;-)
Public holidays have no significance whatsoever in employment law. For example, if you'd normally be at work on the day of the week when Christmas Day falls, your employer has every right to insist that you attend for work on that day, at your normal pay rate, and to take disciplinary action against you if you fail to attend:
http://www.direct.gov...dholidays/DG_10029788
Chris