Issued in 1924, the historic number plate reached £200,000 at an auction in Ayr and was purchased by a buyer in the Midlands.
Auctioneer boss Michael Callan said: “When the hammer went down at £200,000 there was an enormous cheer. “It was a phenomenal price and the number plate is our highest selling item ever. It was a day to remember.
The auction galleries were crowded, with many potential buyers and spectators forced to watch from outdoors. “The bidding started at £60,000 and with a sea of hands the bidding reached more than £100,000 in only a minute.”