Blog post doesn't clarify how these colored coins could get successfully pegged to the pound.

• Issuer would have to be trusted (so much for "decentralized exchange")
• Market would have to trust someone will always be there to buy and sell these colored coins at 1GBP
• No entity, central or aggregate would be able to hold the price pegged without constantly burning wealth in the process (buying and selling at loss to manipulate price free market forces would otherwise randomize)