Persil has been the UK’s favourite washing powder since 1909.
It stood for loving mums taking care of the family’s clothes.
But by the 1990s, it was losing share to Ariel.
Lifestyles had changed, mums didn’t stay at home.
They worked and they needed efficient kitchen appliances.
So they needed soap powders that would remove dirt efficiently too.
Ariel had a more modern image than Persil.
Persil decided they needed to update their image to take on Ariel.
So they developed Persil Power, with a scientific-sounding ingredient: a "Unique Patented Accelerator".
As they prepared for the launch, news leaked to Ariel.
Ariel was owned by Procter & Gamble, Persil was owned by Unilever.
In an unusual move, the top people at P&G approached the top people at Unilever.
They said they’d tried the new ingredient themselves but thought it was too dangerous.
If Unilever went ahead, P&G would have no choice but to come after Persil – it could get very ugly.
But Unilever assumed P&G were just scared.
They ignored the warnings and sent samples of Persil Power to ten million homes.
P&G immediately sent pictures to all the newspapers showing how the ingredient in Persil Power ruined your clothes.
They told the papers: "Use this product and your clothes could become shredded to the point of indecency."
It was perfect for the tabloids, which love scare stories.
Which?, the Consumers’ Association magazine, said Persil’s tests had been conducted on brand new clothes in perfect condition.
But Which? then had 200 people wear viscose shirts and cotton pyjamas for 17 weeks (representing two "person years").
Over that amount of time and washes, the older clothes got faded and frayed.
When these stories ran, many people spotted an opportunity.
A Persil spokesman said they had warehouses full of faded and frayed garments that people had sent in for refunds.
(Even though most of these weren’t actually damaged by Persil but were just people trying it on.)
It didn’t matter: the story ran everywhere and the damage was done.
It cost Unilever £250m to market Persil Power.
But Tesco and Sainsbury’s stopped selling it, so the brand had to be killed off.
Persil had done a lot of tests before they’d launched the brand.
But they’d done all their tests on new clothes.
It didn’t occur to them that no-one has new clothes.
Everyone’s clothes are worn, in some cases years old.
But Persil didn’t do any tests on worn clothes.
So they never saw the problem.
Ariel had done their tests on older clothes, so they knew what the problem was.
But they didn’t tell Persil that.
And when Persil insisted on launching Persil Power with the "Unique Patented Accelerator", all Ariel had to do was tell the papers what they already knew.
By trying to chase what Ariel had, Persil lost the trust that they had built.
This is a common mistake among marketing people.
They think whatever idea they have, they can simply force it into reality.
Which is when they often have a nasty surprise.
Dave Trott is the author of Creative Mischief, Predatory Thinking and One Plus One Equals Three.