There are no 'statutory' holidays. Public holidays have no significance whatsoever in employment law (other than for bank staff, who're covered by specific legislation).
For example, if an employee normally works on Wednesdays, his employer is fully entitled to insist that he works on Christmas Day this year, at his normal pay rate and with no time off in lieu.
Your firm has obviously allocated the two public holidays over the Easter weekend as part of the employee's entitlement but their standing in employment law is exactly the same as those days which the employee has chosen to take off himself.
Therefore the employee is entitled to receive 5 days paid holiday, in lieu of the 5 days that he missed out on.