Are most jobs in London through recruitment agencies or how do you find a job?

I've been looking for jobs in London on several websites, but most jobs are through recruitment or temp agencies that don't want me. How can I go about finding a job in London? It seems like these recruitment/temp agencies are the middleman and you can't apply to most companies directly anymore. I don't live there so far, so it makes it harder. I would want to go there once I get interviews, but I don't get any at all.