Flexible working advice

[iamusuallybeingunreasonable]

Just looking for some advice really... I have asked to flex my hours, so no reduction in hours but change from 9-5 to 10-6. I have done this to accommodate childcare needs that myself and DH will be equally covering. There are also other people doing similar in the firm, so 8-4 and 10-6.

I filled in my form and have been advised by HR they I need to work out how they over the hour between 9 and 10. I have always worked longer than standard hours by blackberry and email into most evenings and some weekends, I can do most things by phone or email and have never let them down (I'm a secretary), so I don't understand why they are being tricky about this.

When it's my time in the evening or at the weekend that's fine but not this, I have committed to remain flexible to their needs as and when, but I need to account for how I will cover off any needs in the hour from 9-10am

Has anyone done this and succeeded in their request?I must say it's making me feel rather bitter!