double pay, what does it say in her contract of employment ?

i don't think there is a set figure for the pay you get working on a bank holiday, wether it's your usual hourly rate, 1 1/2 or double time. depends on your employer.

as for working bank holidays '
Although many workers are given time off work on bank and public holidays, your employer is not required by law to allow you time off work on these days. And if they do give you the time off, they do not have to pay you for this time off. However, your contract of employment may give you the right to time off work on bank and public holidays. If so, it will also specify whether this time off will be paid or not.'

from http://www.adviceguide.org.uk/index/...c_holidays.htm

and from http://www.direct.gov.uk/en/Employme...ff/DG_10029788

'If you work on a bank or public holiday, there is no automatic right to an enhanced pay rate. What you get paid depends on your contract of employment'