Linklaters' close relationship with Vodafone has, until now, always disrupted its relations with other mobile operators. Partner Matthew Middleditch has overcome that, leading the team advising on the E65m (£46.6m) sale of Hutchison Telecom to Carphone Warehouse.
Orange's European general counsel Philippe McAllister said: "We put the transaction out to tender and Linklaters came back with the best reply in terms of quality of the team, knowledge of the matter and in relation to cost."
McAllister acknowledged that Linklaters' German capability also had some influence on the decision, notwithstanding Slaughters best friends relationship with Hengeler Mueller. Linklaters has been wooing Orange for some time, undertaking some small-scale work in Germany and offering in-house training on disposals to Orange's in-house team.
Slaughters and Shearman have been Orange's key corporate advisers on all of its major transactions, including its €6.3bn (£4.5m) initial public offering in 2001.
McAllister said that Orange would continue to put its major transactions out to tender and that he expected to use Slaughters and Sherman in the future.
Shearman will be particularly upset, having lost its position as Orange's parent company France Telecom's pre-eminent adviser on mergers and aquisitions. The firm has both French and German offices.
The Slaughters relationship goes back to 2000 when partner Nigel Boardman advised on the sale of Orange from Vodafone to France Telecom. Linklaters advised Vodafone.
Boardman was particularly close to Orange's former general counsel Mark Paterson, who was replaced when McAllister moved from France Telecom.
Carphone Warehouse was advised in-house by group corporate counsel Tim Morris.