New coin minted for christening of Prince George

The Royal Mint has produced a special coin to commemorate the christening of Prince George. The coin, which has been approved by the Duke and Duchess of Cambridge, features designs including Lily funds from the Tower of London. It marks the first time the Royal Mint has celebrated a birth with a coin, and it was produced in record time. The coin is available in various forms, with the most expensive being a 1-kilogram gold version priced at £50,000. Thousands of pre-orders have been placed, and the coins are set to be available in time for the christening on October 23rd.

What is unique about the Royal Mint's celebration of birth with this coin?

How many coins are available for pre-order?