Mary wore it a month after her pregnancy with Isabella was announced. Has Waity been doing some research on how royals dress in pregnancy?
I know royals aren't allowed to accept free gifts of clothes but are they allowed to borrow clothes from designers? Is it possible that this was on loan to both of them and is in fact EXACTLY the same item?
OR could Mary have kept in contact with Kate since the UNICEF event and now actually be giving her advice and possibly clothes?
I don't think there's any hard and fast rules and it seems to vary from family to family. For example, Queen Rania has been quite open in the past about the fact she borrows a lot of her clothes and much of the rest of her wardrobe is heavily discounted by designers, which makes good financial sense in her situation.
Mary and Kate may have kept in touch but I genuinely find it hard to believe Mary would have given her a coat. Especially as Clarence House like to emphasise the fact that she ( sorry Charles) pays for her clothing.
Birger seems to be a designer that Kate likes and the fact that Mary has also worn clothes by the label is a coincidence IMO. Kate first wore a Malene Birger dress in the summer of 2011 and the UNICEF event was in November 2011.