The Sussex fan took to Twitter to post a photo of the Duke and Duchess of Cambridge arriving at the awards ceremony at Alexandra Palace in north London on Sunday. The user with the handle @XoxoLeigh1, who describes themselves as a "proud member" of the Sussex Squad in their bio, wrote: "No crowds whatsoever lmao."

       The picture shows the Cambridges walking into the venue which is sealed off by metal barriers.

       Another user, @ma56138929, commented on the post: "Lmao they put up barriers but there are no crowds."

       A third, @SussexRoyalGlow, added: "OMG !!! I walked past there yesterday about 6:20pm. Literally across that car park in this picture. I didn’t know something was going on there. It looked like normal."

       One more, @SueSueD, wrote: "Don’t matter how hard they try they just ain’t got the x-factor."

       However, another Twitter user with the handle @jozzzaphen claimed the angle the picture was taken made it appear as if there were no onlookers.

       They said: "The crowds were on the other side, that area was closed off to the general public."

       William and Kate attended the inaugural Earthshot Prize awards ceremony on Sunday evening.

       The Duke launched his prize to find solutions to the planet's environmental problems.

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       It features five categories, or Earthshots, and the winners each received ￡1 million to develop their initiatives.

       Among the winners were projects restoring coral reefs, redistributing unwanted food to the disadvantage and battling the issues contributing to air pollution in India.

       Kate looked stunning in a pale purple Alexander McQueen dress for the awards ceremony, while William wore a dark green velvet blazer and a polo neck.

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       At the end of the event, televised by the BBC, William took to the stage to tell the audience: "I want to say something to the young watching tonight.

       "For too long, we haven't done enough to protect the planet for your future, the Earthshot is for you.

       "In the next 10 years, we are going to act.

       "We are going to find the solutions to repair our planet.

       "Please keep learning, keep demanding change, and don't give up hope.

       "We will rise to these challenges."

       The winners all appeared via video link to give their reaction to receiving ￡1 million to develop their initiatives by the decade-long award scheme.