When ‘The Sun says…’ do it, we environmentalists always get excited.

Back in 2002, the newspaper wrote what was probably climate change’s most grabbing headline: ‘Where have all the tits gone?’ This week it’s engineering the biggest ever giveaway of energy saving lightbulbs – the largest single order in the history of this much-misunderstood eco-product.

Tomorrow morning, several million Sun readers will come back from the newsagents with not only their staple reading under their arm, but a twin-pack of low-energy bulbs. “No vouchers, no fuss,” the man on the end of the customer helpline told me.

The 4.5 million they’re distributing certainly promise much quicker results on the big lightbulb switch than the government’s gradual, voluntary phase out of incandescents by 2011.

Of course giveaways don't guarantee a complete turnaround in people’s habits – readers who enjoy a good freebie might not actually buy an energy-saving bulb next time round. To take an analogy, Brits can get their hands on no end of free condoms, yet that hasn’t stamped out teenage pregnancies.

But you’ve got to hand it to whoever came up with this idea – some bright spark at Southern Electric, who is providing the goods, I imagine – for actually getting these gadgets under people’s noses and showing the sceptics that they can light a room properly. The Sun itself ran a scare story on the health risks of these bulbs just two weeks ago, so boy, nothing less is needed to bring the masses round.

I know that getting them into people’s shopping baskets is only half the battle, and you might ask if anyone will bother to fit them. I mean, do we know how many Sun readers it takes to change a lightbulb?

Luckily, the organisers have got a pretty good idea, and have slipped in a bit of Charlie and the Chocolate Factory-style magic to the story: just ten special bulbs will glow green when switched on, meaning you’ve won a holiday or a Toyota Prius.

I can already picture them stacked up behind the counters at WHSmith and Tesco ready for the morning (the shop assistants must be dead pleased about that). Let’s only hope the bulbs go down as well as those chocolate bars did.