Holidays and returning to work part time after maternity leave

The minimum holiday entitlement is 28 days per year (which can include bank holidays 8 days) So, unless her contract gives her more than this she is entitled to 28 days / 5 day week x 4 day week = 23 days including bank holidays (holiday pay can not be rounded down). Just pay her a 'normal' (i.e. 5 hours a day) pay when she books holidays. Same for bank holidays. If a bank holiday falls on a day she doesn't normally work don't pay her anything.
I think I'm right in saying that whilst she was on maternity leave she will have accrued holiday pay at her 'full-time' rate so you may need to adjust this years entitlement accordingly.

Hi, I wonder if someone can point me in the direction of some regulation relating to returning to work from maternity leave to flexible hours/part time.

An employee who worked full time went on maternity leave last year and is returning to work in March. Her request for flexible working hours has been agreed, and she is coming back for 5 hours a day for 4 days a week. This equates to approx 75% of her full time hours and therefore she is entitled to approx 75% of her full time holiday entitlement. However she has asked that this holiday entitlement is then converted into the appropriate hours as if she takes a 'day' off, it is actually 5 hours NOT a full working day.

Therefore, if she is entitled to ten days holiday (as an example) and a full time day is 8 hours, she then has 80 hours holiday. So if she takes a day off, she simply deducts 5 hours from this total.

Is this correct?

Also what is done about bank holidays? Are the added to this total? Are they pro rata-ed like holidays?

We don't have an issue in agreeing this, however are looking for some definitive advice on how to treat it as it will set a precedent.

any advice would be appreciated! Thanks so much!