I'm sure her gold coin must be dated 2009 as it would be a poor presentation if they said "congratulations, we will give you a gold coin in 2 years time".
Insistently, presumably the gold Olympic coins would be produced from proof dies, which means they would have been produced separately from the dies used for the BU Set & circulating coins, therefore there could be other design differences.
Also was Jonathan Olliffe's gold Aquatic 50p an under water one?
Ian..