Google is under fire for a data privacy breach way back in 2011-12, and could have to pay out big time to compensate iPhone users.

The UK-based campaign, “Google You Owe Us,” is being helmed by former Which? executive Richard Lloyd on behalf of 5.4 million Brits. The campaign says that Google used a nefarious workaround to bypass Safari’s default privacy settings in iOS, allowing it to store cookies, harvest personal data and publish targeted ads without the user’s permission. Google has already been in hot water for this exact offense, paying a $22.5 million fine for violating user privacy in 2012 – but users have never before been represented in this way.

The privacy violations took place between June 2011 and February 2012. During that period, if you lived in England or Wales, owned an iPhone, and had an Apple ID, you’ll be automatically included in the lawsuit and will be due compensation if it’s successful. The exact payout is unclear, with various sources estimating anywhere between £200 and £500 per person. Not chump change by any means.

Lloyd said in a statement that he hopes to “send a strong message to Google and other tech giants in Silicon Valley that we’re not afraid to fight back if our laws are broken.” He added that “in all my years speaking up for consumers, I’ve rarely seen such a massive abuse of trust where so many people have no way to seek redress on their own.”

Whether similar legal action could be taken around the world is yet to be seen, but if Lloyd gains much traction in the UK you can bet it won’t be long until a global campaign is launched.

You can read more about the campaign here: Google You Owe Us.