PERFECT PAIR: Joshua Tanuvasa and Erin Barter at the Hamilton Girls' High School senior ball.

There was a fine moment on the night of September 22 when an elegant Erin Barter posed for a photo next to dapper Joshua Tanuvasa at the Hamilton Girls' High School senior ball.

The photo of the best-dressed male and female has developed a tragic sadness since that day.

Last Monday, Erin, 18, died after a battle with cancer.

Two days later, Joshua, a seemingly fit and healthy 17-year-old, died after collapsing at Les Mills gym.

Erin was farewelled last Thursday at Waikato University's Lady Goodfellow Chapel.

"I can understand why she got the belle of the ball," Erin's grieving mother Corinne Nicholson said.

"She looked beautiful. Absolutely stunning on the night and her beautiful ballgown - it was one of her best nights."

Family in Britain couldn't believe how radiant Erin looked in spite of the acute myeloid leukaemia that was progressively destroying her bone marrow.

Erin had been a sporty, healthy girl, Ms Nicholson said.

In 2010 she tackled the Huntly Half Marathon and she was particularly passionate about adventure racing.

It was while training last year that she started to become unusually lethargic.

Ms Nicholson thought it was glandular fever but on October 10 a doctor diagnosed Erin with acute lymphoblastic leukaemia.

She soldiered through major chemotherapy to destroy the cancer cells and in February underwent a stem-cell transplant.

Things got better. Her health improved. She flourished, Ms Nicholson said.

But in July, she relapsed.

And this time the cancer was far more aggressive.

"She wasn't supposed to see her 18th birthday or meet her niece but thank God she fought the battle right to the end and reached many milestones."

The ball was one of them.

Although Ms Nicholson said it was the night of Erin's life, there's a melancholy about her in the ball photo.

Joshua on the other hand looks every bit the young man his friends and family have been describing since his death - loving, caring.

A young man who held his mum closest to his heart.

Ms Nicholson was shocked to hear of his death.

"We were looking on Facebook the other evening and I couldn't quite understand it. I thought someone had made a mistake, then I had phone calls the following morning. I thought, ‘My goodness that poor family'. My heart goes out to them too. With losing Erin, at least I had some warning."

One of Joshua's many friends, Hayley Waretine, will be one of more than 1000 mourners expected at his funeral at the Gateway Christian Centre this afternoon.

Hayley tracked down Joshua's hired ball suit and, after hearing his story, staff sold it for $350 - the jacket alone was worth $600.

Today he'll be farewelled, then buried in it.