Accrual of Public Holidays during Maternity Leave

SMP increased from 6 April 2008 to 39 weeks paid maternity leave.

Our policy states that “employees are entitled to time in lieu for any public holidays which fall during the first 26 weeks of paid maternity leave”.

I’ve read conflicting maternity legislation and am now unsure whether the accrual should be based on the first 26 weeks as before or 39 weeks?