Who are the external auditors of Tesco plc? What part did they play in resolving the scandal?

Research into any high-profile corporate fraud case for which the amount involved exceeds £249 million  and briefly discuss the role played by external auditors in the scandal. You must also identify the audit approach and/or procedures used by the auditors prior to the fraudulent activity being exposed and lessons learnt from such a scandal.
Give a Case summary
This should be 400 words/one page long. The summary should include: 2 lines on who Tesco plc is, what happened, how was the fraud found out, what was the intention of the fraud, what effects did it have on stakeholders . What were the penalties?
Role of external auditors in the scandal
Who are the external auditors of Tesco plc?
What part did they play in resolving the scandal?
Audit approach & procedures taken by the auditors
What were the auditors accused of?

Lessons Learnt from this scandal
Were there any changes to policies/rules after the scandal? What has the world learnt from the Tesco scandal? What are the penalties of such scandal?