The bag is easy to fasten particularly considering I haven't removed the protective covering over it. It is sturdy and I don't think there would be an issue with it popping open. Also, the bag is not wide open unless you pul the side straps (for lack of a better word) all the way out. Even doing that I had to pull the bag open. At this time and never have carried it, I can't believe it would fall open unless it was totally over filled.
The bag that looks rose colored in the Harrods picture interests me because I think it is possibly the color I have. In the US the color rust is generally much darker so I was surprised when it arrived. Frankly, it was a good surprise. There is no doubt my rust bag has a pink hue to it. I could be mistaken but my bag is not the dark color shown in the Mulberry advertisements. I am interested to hear what you find in Germany. Also interested to see what you think of the two sizes. My bag is the same size as the medium
Prada Galleria. I am very happy with the Mulberry and the quality is on par with any high end bag.