44 per cent of the Guardian’s global web traffic in April came from smartphones and tablets. The figure was revealed a couple of minutes ago by the Guardian revenue director, Tim Gentry, on the IAB’s Mobile Engage event.

Gentry also revealed that on the weekend, 55 per cent of the Guardian’s football content web browsing occurs on smartphones and tablets, and that during the last quarter, 11 per cent of the Guardian’s advertising revenues came from cross-platform solutions, all of which had mobile on the heart of them, across many sectors, including fashion, retail and mobile. He told delegates: “I think the explanation mobile is on the heart of those packages is since it is on the heart of our business.”

Earlier, kicking off the development, IAB chairman, Richard Eyre, issued a rallying call to brands to get their mobile act together. He noted that too many brands’ websites are still not optimised for mobile, and told delegates:  “We wish to fix this. Analyze your company’s website on a mobile device, and if it doesn’t work, return and shout at someone. Mobile first is not very creativity; it’s hygiene.”

Eyre then said that we’re seeing “the end of advertising as we all know it”. He explained that, with the arrival of mobile, advertising is “no longer a device for managing remote audiences firing messages from beyond enemy lines”.

He said: “For the last 100 years, just about all promotional messages has been separated from a purchase order opportunity by time or place… The recipient needed to act upon the message at once more. Now, the message lives next to the acquisition opportunity…It means brands will also be portion of the conversation, talk in an ordinary voice. Now we have been upgraded from shouting down potential customers to working with them, having amusing with them.”

But Eyre cautioned that success on mobile hinges on permission, and that a precondition of it truly is trust. “Every brand must be doing what it should do to become the foremost trusted brand in its sector,” he said. “The opportunity is all there, unless a brand betrays that trust, after which it’s gone.”

He ended by urging brands to disregard the temptation to consider mobile as just another screen to stay ads on.

We’ll have more from the development in the course of the day, subject to hearing interesting stuff from the speakers obviously.