Bommert warned other partners he would leave during early consultation over the merger.
Boesebeck Droste's deputy managing partner Oliver Felsenstein says: "His client base was domestically orientated and he did not believe in our international strategy. He wanted to be in a firm which concentrated on the domestic market and Haarmann has clearly declared it will not merge.
"He is the only one to have left after the merger. When you have 230 partners you cannot keep everybody happy. Lovells were aware of his feelings before the merger went ahead.