Peter B. Denniston, president and chief executive...

Peter B. Denniston, president and chief executive of developer Signal Landmark, has resigned to start a consulting firm after Signal’s parent company hired an outside firm to oversee Signal’s operations. Denniston, 38, joined Irvine-based Signal Landmark a little more than two years ago. But parent company Henley Properties Inc. in June hired Koll Co., a Newport Beach developer, to manage its buildings and development projects. Koll hired about 20 Signal Landmark employees and fired about 25 others.