Mike:
The statutory holiday entitlement (for someone who works 5 days per week) was originally 20 days. Some employers chose to take that as meaning 'in addition to public holidays', while others chose to take it as 'including public holidays'. The Government decided to act to create uniformity and (in a two stage process) changed the entitlement to '5.6 times the number of days worked per week, subject to a maximum of 28 days', with the understanding that such entitlement should include all 'enforced holidays' (when the business was closed), irrespective of whether such days were actually public holidays.
The DirectGov website quotes those rules and specifically states:
"You do not have a statutory right to paid leave on bank and public holidays. If your employer gives paid leave on a bank or public holiday, this can count towards your minimum holiday entitlement".
http://www.direct.gov...dholidays/DG_10029788
Chris