Lovells managing partner for Continental Europe Harald Seisler said: "It's essential that we have this. In the last year we've improved profits considerably, but we now want to increase the quality of work."
"It's closer to the one-firm approach. Pitches in Madrid or Germany don't look different."
Each European office of the firm used to handle its own business development and client marketing with some input from the London management. In her new role, Warren will supervise all offices from her base in Frankfurt.
Seisler said: "It used to be done on a local basis, with some coordination from London, but you can't oversee everything that way."
"There are 15 offices in the region and this is good for cooperation on business development."
Seisler said Lovells is looking to build on its dispute resolution practices across Europe. Last month the firm hired Jürgen Witte from German independent Aderhold von Dalwigk Knüppel in Düsseldorf.
Frankfurt-based Seisler was elected to the Europe managing partner role in 2005 for a three-year term.