A piece of cake from Prince Charles' Wellington birthday party has appeared on Trade Me.
Listed by Wellington seller Sandy Jamison, the auction promises a ''one-time opportunity to have Prince Charles' birthday cake and eat it too''.
Bidding had reached $100 by 9.15 am today - 12 hours before bidding closes .
Jamison said the cake came into her possession because both her partner and son-in-law shared the same birthday as the prince, November 14.
On Wednesday, Prince Charles celebrated his 64th birthday at Government House with 64 Kiwis who shared his birthday.
Her partner - born five minutes before the prince - and son-in-law both entered the draw to attend the party, but just her son-in-law won, meaning he celebrated turning 51 at Government House.
''We were quite disappointed, so they felt really sorry for us and gave us the other piece of cake.''
Guests were given two pieces of cake to take away. The piece for sale was from the official fruit birthday cake for the prince.
She listed the piece of Trade Me for a laugh. ''It's just been hilarious. We are having some friends around at 8pm when it closes, having a sausage sizzle and watching it close.''
She said she had been ''stunned'' by the response to the auction.
''I didn't realise there were so many royalists in New Zealand.''
Her son-in-law appreciated the humour of the auction.
The slice of cake was wrapped in a gold-coloured box with a royal seal.