Magic circle firm Clifford Chance has changed its Big Four auditor after a decade, awarding the £1m-a-year contract to PwC with the resignation of longtime incumbent Deloitte, the Gazette understands.

In a letter posted this week by Companies House, Deloitte gave formal notice of its resignation with immediate effect on 6 February.

The correspondence added: ’There are no circumstances connected with our resignation which we consider should be brought to the attention of the members or creditors of the LLPs and companies.’

The Gazette understands the decision was taken by the law firm after a routine tender process.

According to accounts for 2013/14, Deloitte was paid a total of £939,000 in fees by Clifford Chance LLP last year. This comprised £533,000 in fees to the auditor, £280,000 in non-audit fees for services such as tax compliance advice and £126,000 in respect of the auditor’s associated pension schemes.

Deloitte also resigned as auditor as Clifford Chance LLP subsidiaries Clifford Chance International LLP and Clifford Chance Europe LLP.

Clifford Chance ranks among the top 10 law firms in the world by revenue, with turnover reaching £1.36bn in 2013/14.