We created a new mechanism: “Divine Sampling”.

We know that word of mouth is incredibly powerful, but we discovered an even more effective channel: Word of God.

With so many Israelis unwilling or unable to recognise they had dandruff, we recruited the most powerful advocate around, their religious rituals.

While families carried out their devotions for Passover, including removing any bread crumbs in the house, we would add dandruff to their removal lists.

We would do this by making Head & Shoulders part of the Passover, including special dandruff detection strips in the traditional search kit of candle, a feather and a dustpan, all used to symbolically locate, swipe and remove any tiny suspicious objects.

We bought the entire national stock of Passover kits from the sole supplier; a quarter of a million packs containing a candle, a feather and a dustpan used to symbolically locate, swipe and remove any tiny suspicious objects.

We branded each kit with the Head & Shoulders logo and added dandruff testing strips, so that the search for unwanted objects would encompass flakes of dandruff.

In previous years, Passover kits could only be purchased at supermarkets and grocery stores, but we arranged for them to be distributed via synagogues – a first for a brand, and acceptable because the Passover kit contained the text of a key prayer.

We even set up a hotline that people in need – the handicapped and the elderly – could call and get their homes inspected for them.

This activity was supported by heavy print activity and extensive PR.

We are proud that we didn't simply replicate the global strategy to distribute the test strips through print.

By ensuring both the means of distribution and the context of the message were culturally relevant, consumer receptivity to our message was significantly higher.

We earned US$130,000 worth of media coverage for our activity. There were dozens of calls to our hotline number, which also helped drive PR coverage and featured prominently in our print ads.

The 250,000 Passover kits were all distributed, ensuring that our test strips reached the homes that need them.

Sales soared. H&S’s market share grew by 35% year on year.

P&G plans to repeat the H&S Passover programme in 2016. We plan to replace the candle with a branded mobile flashlight app.

If you want to change consumer behaviour, you have to reach them in a way that is culturally relevant.

Our inspired consumer insight – which connected Passover and the search for dandruff for the first time – reinvented the global strategy for Head & Shoulders and made it compelling in Israel.

We got Israelis to use the traditional pre-Passover search for “unKosher” bread crumbs as an opportunity to test for dandruff flakes, boosting sales by 35%.

We created a brand new, inspired and winning sampling exercise by creating “Divine Sampling”.

The key to making Israelis realise they needed Head & Shoulders was to create a moment of introspection and cleaning; a moment when they would honestly look in the metaphorical mirror and acknowledge the white flakes in their hair.

And we realised that Israelis already had just such a national moment – the Jewish holiday of Passover – even if this moment of honesty involved crumbs of bread rather than flakes of dandruff.

No bread is eaten during Passover. In fact, even the tiniest crumb hiding in a dark corner of the house is believed to leave its occupants exposed to divine punishment.

The tradition is that everyone conducts a formal search of the house by candlelight, disposing of any “unKosher” or “Chametz” elements.

Our strategy was to leverage this national preoccupation with keeping a 100% kosher home as the perfect analogy for keeping a 100% dandruff-free head.

Half of Israelis will suffer from dandruff at one point or another in their lives, creating huge headroom for Head & Shoulders, whose brand promise is to be 100% dandruff free.

But many people don’t buy H&S when they get dandruff, because they don’t actually know they have dandruff – and their friends are too embarrassed to tell them.

H&S’s global solution to this conundrum, which was found in many markets, was to develop a new kind of dandruff self-test: a black strip that could be held to the scalp for a few seconds to see how much dandruff it picks up.

The global strategy was to distribute the self-test strip with print.

Our concern was that such a strategy wouldn’t be effective in Israel. Most of the target market would simply turn the page.