One of the UK's leading bookies Paddy Power have already paid out on the newborn Prince's name after a flood of bets were placed on a clear favourite.
Arthur is now a 7/4 favourite for the newborn baby boy, odds which Paddy Power say have forced them to pay out on the bets.
A spokesman for Paddy Power told The Sun: "Kate and Will might be keeping tight-lipped, but we think enough people have Arthur clue as to the name. Rumours have been swirling all day, and we've seen a royal flood of bets on Arthur, forcing us to pay out early."
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The Sun also reported that Prince William pointed out one of their cameraman called Arthur when he left the Lindo Wing of St Mary's Hospital today and exclaimed "there's Arthur," adding fuel to the fire.
The odds firmed on Arthur after a mystery punter placed a whopping $10,000 bet on the name not long after the birth.
The names James, Albert, Philip and Thomas are also popular among punters, but nowhere near the frenzy which has surrounded Arthur.
The Prime Minister said New Zealand will be sending several gifts to Prince William and Kate.
The public shouldn't have long to wait for the big reveal, with the names of Prince George and Princess Charlotte being made public no later than two days after they were born.
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