Clifford Chance (CC) has won a spot on BG Group's UK legal panel, ousting Herbert Smith Freehills (HSF) and Allen & Overy (A&O), after the energy giant concluded a review of its external advisers.

CC joins fellow magic circle firm Freshfields Bruckhaus Deringer as a full service adviser to the FTSE 100 company, while CMS Cameron McKenna has also won a spot.

The omission of A&O and HSF from the roster will come as a shock to much of the market, after several sources close to the pitch process had said they expected the roster to remain unchanged.

An exhaustive seven-month panel review process in 2010 led by general counsel Graham Vinter (pictured) saw the company trim its key legal advisers to Freshfields, CMS, HSF, and A&O.

The 2010 process also saw Linklaters lose an official seat on the reduced panel.

The arrangements, which came into effect on 1 November, follow a relatively short review process – first reported by Legal Week – with firms initially having been invited to tender for places in September.

BG Group operates four panels to service its global operations, with the UK panel sitting alongside similar structures in Brazil, North America and Australia.

Major mandates since 2010 include Freshfields' role on BG Group's $470m (£291m) disposal of a stake in India's Gujarat Gas, and CMS' Brazilian office's work advising on several unincorporated joint venture arrangements.

In June A&O and CMS joined BG Group as part of a business delegation accompanying Prime Minister David Cameron on a trade visit to Kazakhstan.

BG Group has also shown that it is prepared to go off-panel on certain mandates. Last year Linklaters won an appointment to advise the company on its remuneration report, with HSF taking a subsidiary role.

"Following an extensive review of its UK Legal Panel, BG Group has appointed Clifford Chance as a full service firm to its panel alongside existing firm Freshfields Bruckhaus Deringer," confirmed a BG Group spokesperson in a statement.

"CMS Cameron McKenna also retains its place on the panel. The arrangements took effect from 1 November."

"We are thrilled to be appointed to the panel and for the fantastic addition to our corporate client base," commented CC senior corporate partner Guy Norman, who led the firm's pitch.

"We very much look forward to working with BG on the opportunities and challenges they face as a world leader in exploration and production of natural gas."

Norman recently returned to London from Dubai, where he was based for three years as regional corporate head.