My understanding, but I am not certain of the legal position around itso don't quote me, is that if you request to return part time when you return to work that your employer has to present a business case for why part time isn't possible. If they are unable to do so I believe they are obliged within reason to agree to a part time arrangement. I think this is why so many people (mainly mothers) are able to return to work part time after having a child. I think this is legislation rather than what your individual parental leave policy is.