We have found out that there was an error in the price matrix for GB Pounds, and had set the Deluxe Edition at an error price. We have submitted the corrected price of ￡48.49 (instead of ￡54.99) pending Valve's approval.
In the meantime, for customers who have purchased the product at the wrong price, we seek your kind understanding and cooperation, and kindly file for a refund to Valve via the reason of price error.
We deeply apologize for the inconvenience and confusion caused.
Edit: For all those who have got their request rejected, kindly leave a post in the comments, I'll tabulate and send it up to Valve myself.
Edit2: June 15th - Above request filed to Valve for 5 members.
Edit3: June 19th - Valve has responded that the request had been fulfilled.