Need Pest Control Advice in London

Has anyone dealt with a pest infestation at a home, restaurant, office or commercial property in London? I'm looking for advice on finding a professional pest control service in london that provides effective treatments and doesn't just deal with the problem temporarily.

I'm particularly interested in services for rats, mice, cockroaches, ants and bed bugs , along with inspections and preventative pest management. What should I look for when choosing a pest control company?