More than four million iPhone users could be in line for a £750 each in compensation from Google, after it lost a landmark case at the Court of Appeal.

Judges ruled on Wednesday that the search giant had conducted unlawful and clandestine tracking of iPhone users in 2011 and 2012 without their consent through the use of third party cookies.

Google could face a bill of up to £3.3bn from UK customers for allegedly gathering and sharing the personal ­information of millions of iPhone users in the UK by bypassing the default ­privacy settings on the Apple device between June 2011 and February 2012.

The Court of Appeal claim was led by former Which? director Richard Lloyd, who set up a consumer campaign called Google You Owe Us as part of this legal action.

Claimants alleged Google violated ­iPhone privacy by effectively tricking devices into releasing personal data from the Safari web browser. This has become known as the “Safari Workaround”.

They told the court that data collected included race, physical and mental health, political leanings, sexuality, social class, financial, shopping habits and location data.

The claim group hopes to win at least £1bn in compensation for an estimated 4.4 million users affected.