Have you asked a Mulberry store to clean it for you? When I bought a Mulberry in NYC several years ago, I was told there was a lifetime warranty and that I could bring it in at any time for cleaning/restoration. A few months later, I carelessly left it sitting on the kitchen counter, where it got Thai green curry splashed onto it. I initially freaked, but I took it back to the store and they didn't blink -- a couple weeks later, it came back to me as good as new.
My Mulberry is the most expensive handbag I own, and it's frankly the level of assurance they give that made me willing to pay so much for it.