I was really dubious about this, as it seems to be a great policy but could ultimately cause the death of a company if things go slightly wrong.
Well, after an email or two, the company said they'd exchange my shoes. So I jumped on the train and took them back to the Covent Garden store. They knew I was coming and after explaining the problem, I left with a replacement pair without any fuss. Impressed.
Of course, I had a good look at all of their other shoes whilst I was there. Niiiiice.