Tilly Smith was ten years old.
Tilly, her little sister Holly, and her mum and dad, were all on holiday.
They’d gone to a sunny place called Maikhao Beach.
They got up early and walked along the beach in the sun.
As they were walking, Tilly noticed the tide had gone out.
A very, very long way out.
She also noticed that the water was frothy, just like a pint of beer.
She stopped dead.
This was exactly like the newsreel film her geography teacher had shown her back at school in Surrey.
Mr Kearney had shown her class some old black and white footage of Hawaii in 1946.
It was the only film anyone had ever seen of a tsunami.
In fact most people hadn’t even heard the word tsunami.
But Tilly was convinced that was happening right now.
She tried to explain to her mum what she thought was happening.
Her mum wasn’t convinced, obviously.
No one had heard of a tsunami.
No one on the beach, including the life guards, was taking any notice.
So this probably happened all the time.
How could a ten year old girl from Surrey know more than the people who lived and worked here?
Tilly started to yell at her dad.
She was positive this was the thing Mr Kearney had shown them two weeks before.
Her dad had a difficult choice.
Listen to his ten year old daughter, who was getting hysterical.
And maybe cause panic on the beach.
Or ignore it and just take his daughter back to the hotel until she calmed down.
But what if she was right?
All these families, all these children, would die and he’d be responsible.
For an Englishman, embarrassment is the worst thing of all.
But he decided he had to take a chance.
He told the security guards, who told the lifeguards.
The beach was cleared and everyone went back to the hotel and climbed to the third floor.
They didn’t have to wait long.
In less than a minute the first of three giant waves struck.
In fact giant waves struck beaches all over South East Asia that morning.
It was the Boxing Day, 2004.
In a few hours everyone in the world knew what a tsunami was.
Because that tsunami killed a quarter of a million people on beaches in thirteen different countries.
But there was one beach where no one died.
The beach Tilly Smith had been on.
That was the beach everyone left before the wave struck.
Because ten year old Tilly refused to shut up.
She wasn’t old enough to be silenced by crushing embarrassment.
She was still young enough to know she was right, and not allow herself to be quietened down.
Later, she was taken to the United Nations, where she was publicly congratulated by Bill Clinton.
Because Tilly saved the lives of over a hundred people.
Men women and children.
By being unreasonable.
By insisting on being heard.
Instead of wishing she’d spoken up after it was too late.
That’s something we could all do with learning.
Regret is worse than embarrassment.