BT's takeover of EE began with a money dance.

The custom dates back to early 20th century Poland, when male wedding guests paid to dance briefly with the bride.

In 2014, a modern take on the tradition surfaced in the European telecoms sector. At this time, the UK's largest mobile operator EE and its rival O2, owned by Spain's Telefonica, were both trying to woo BT.

"Both sets of owners had to more or less dance around the potential bride until she came up with an offer," recalls Clifford Chance corporate partner Joachim Fleury, who advised Deutsche Telekom on the deal, which co-owns EE with Orange. "It was an unusual process with a reverse auction. In a normal auction, which the seller organises, everyone tries to bid the highest. Instead there was pressure on the price."

Following intense negotiations, BT selected EE as its merger partner in December that year and the key documents were signed in February 2015.

"It was a turnaround of less than two months for one of the largest telecoms deals in Europe in recent years," comments Norton Rose Fulbright partner Oliver Stacey, who advised Orange. "Competition in the European telecoms market is fierce and deals need to be concluded swiftly for both buyers and sellers."

Fleury adds:

"I remember taking conference calls on Christmas Day and on the weekend between Christmas and New Year to get all the due diligence done. It was such a big deal so there was a lot of pressure on it."

By sector, telecoms was the most active in 2015 with three deals in the European top 10. While BT-EE was the largest, other sizeable transactions completed last year include Nokia on its €14.7bn (£11.6bn) takeover of French rival Alcatel-Lucent.

The BT-EE merger legal team:

Stone throwing

Although the BT-EE deal was ultimately cleared unconditionally in January this year, it faced multiple objections.

And the UK's largest fixed-line business remains under pressure as Ofcom has said it must open up its cable network to competitors in order to reduce its dominance in the market. The regulator has not yet demanded a complete break-up of BT, but said this was still an option.

During the course of a year-long probe, from the initial merger submission to the Competition and Markets Authority (CMA) in May leading up to the competition watchdog releasing its provisional findings in October, BT faced complaints from multiple rivals.

Key complainants included Vodaphone, Virgin, Talk Talk, O2 and Sky. They feared that that the combined group would have too much power to undercut the prices of their own services.

"Their number, determination and sophistication were a real challenge for BT. Many third parties had clearly instructed lawyers and economists to help them throw stones at the merger," comments Freshfields Bruckhaus Deringer competition head Rod Carlton.

BT brought in its key corporate adviser Freshfields to assist its in-house legal team on the deal. The magic circle firm put forward Carlton alongside corporate partners Natasha Good and Ben Spiers and three associates. It also employed economists from UK consulting company CompassLexecon.

Carlton worked primarily with BT's head of competition Bruce Breckenridge and three other full-time BT lawyers on the deal.

"On the competition side, we worked to our respective strengths, with BT lawyers having a deep understanding of BT and the markets in which it operates, and the regulatory environment, and Freshfields having extensive experience and expertise in engaging the CMA on seeking clearance on significant transactions," says Breckenridge.

Despite the efforts of the complainants, the deal process was eased by the fact that BT and EE focus on two different sides of the market (fixed line and mobile). And ultimately, none of the objectors sought to appeal the CMA's clearance decision.

In comparison, O2 is currently embroiled in a more controversial battle to merge with UK rival and fellow mobile network Three owned by Hong Kong investment company Hutchison Whampoa.  

UK regulator Ofcom is pressing Brussels to block the proposed £10.3bn merger of announced last year on the back of fears that UK consumers' mobile phone bills will rise sharply.

With its rivals pushing to follow a similar path, there's no doubt that BT-EE has dramatically shaken up the UK telecoms market. 

As Carlton concludes:

"This was undoubtedly a challenging case: a pioneering transaction bringing together the UK's biggest fixed network and biggest mobile network in an industry facing structural, technical and commercial change."