I've only gone and ordered the tan one too. I found it on Monnier Freres. It's an extra £35 but I would normally opt for brown over navy and won't be buying another bag for a long time so won't to go for something that'll go with most things.
Mixed reviews online about Monnier Freres. Quite a few saying that their orders for sale stuff actually couldn't be fulfilled and had to wait for a refund. I'm surprised the brown one was reduced.
Just hope I can return one of them ok.