Hannah Sergel was among the huge crowd that turned out to greet Meghan and Prince Harry at the Viaduct Harbour in Auckland, on New Zealand's North Island Tuesday.

The young woman confided about her health problems with Meghan Markle before, and the Duchess of Sussex was astonished after she spotted her among the crowds.

The 20-year-old and Meghan used to message one another on Instagram before the Duchess deleted her account following her engagement to Prince Harry.

Before she got together with Harry, Meghan sent the young woman a short video clip and messages of inspiration encouraging her to be herself and work hard at university.

Hannah, who talks about her battle with mental health on Instagram, was left in tears of joy when the Duchess recognized her among the thousands of adoring royal fans.

Meghan's jaw dropped the moment she spotted Hannah, who had flown across the country for the chance to meet her idol.

'Oh my god', the Duchess exclaimed as she rushed over to greet Hannah, who was holding a 'It's Hannah from Instagram' sign.

The Duchess gave Hannah a warm hug and accepted a letter she had written. It was the first time the pair had met in person.

Hannah said Meghan's jaw-dropping reaction 'means the world to me'.

She later posted on social media how shocked she was to finally met her idol.

Hannah said the Duchess has been an inspirational figure in her life.