The father of New Zealander Erena Wilson, killed by a falling tree branch at Kew Gardens in London, has spoken of his pain at her death.
Chris Wilson has vowed to fight to honour her name by getting the phenomenon he believes caused the branch to fall to be recognised worldwide.
Wellington-born Erena, 31, died at the Royal Botanic Gardens Kew in September 2012 after a cedar tree branch fell on her after a storm.
Experts blamed "summer branch drop", a rare phenomenon that causes branches to fall when heavy rain follows drought.
Chris Wilson, a former Wellington police officer, is campaigning for visitors to public gardens to be warned about the dangers of summer branch drop.
He is doing so in spite of an inquest jury finding last month the death was an accident not caused by summer branch drop, and that Kew Gardens were not at fault.
Speaking from his Sydney home, Chris Wilson said: "It's a devastating thing. You hear people say this after a death, especially the death of a child.
"It's a funny thing, in some ways I had to keep checking in on myself with this process. Are you doing this for the right reasons?
"Is it something you're doing for your daughter because you couldn't be there to save her?
"Maybe that's part of it but there's more to this – it's the questions that need to be answered, until I get to the right answer."
Emotionally hard-hit, the Wilson family are learning to cope with their loss.
"Were getting through it. You have to get on with your life. There's a shadow that walks with you and sometimes that shadow falls across you and you take a break and let it overwhelm you.
"It can be triggered by something you see on TV or kids on a bus that take you back to the moment. We'll get on with our lives but they won't be the same without her."
Looking for answers helps him cope.
"I didn't know anything about this when I started. I'm a layperson but the more it came to light and the more research we did about it independently and with [British tree expert] Jeremy Barrell's assistance the more it became a worldwide thing.
"In different jurisdictions around the world they seem to take it a lot more seriously than in Britain. It's one of these things where people say it's a freak with only one in millions of chances of happening, but so is an avalanche and many other things. I don't see why it's not more widely recognised."
The phenomenon should be called sudden branch drop rather than summer branch drop as it was caused by specific weather conditions that could happen at any time "given the way the climate is changing these days".
Actions to stop death from summer branch drop "don't have to be a huge thing" such as fencing off all trees, Wilson said.
He suggested gardens open to the public put up website warnings after long dry spells when weather conditions might be conducive to falling branches.
Signs at entrances or next to trees that grew over major walkways would be useful and needed to be in place for only six to eight hours after sudden downpours.
Australia "deals with it really well" with councils putting out warnings at different timesCanada did the same, Wilson said.
He argued that warning would be "the same as getting golfers off a course when there's a lightning storm," or avalanche-warning signs on snowfields.
"It's a certain set of conditions that leads to these things happening. It's a scientific process within the tree and not just a random act.
"I don't want to be fist shaking at Kew, it's about awareness into the public domain."
After the inquest in June, Kew horticulture director Richard Barley said the jury had found there was no identifiable cause of branch failure from the tree that killed Erena Wilson.
The independent expert said there was nothing that could be foreseen, no action he felt could or should have been taken, and the trees were managed in an appropriate and responsible way.
"Summer branch drop is a very loosely defined phenomenon," Barley said.
"It's not well researched and there's very little data on it and, hence, I think it is unfortunate to seek to make, as in this case, something fit that loose definition."