Industry Question - Publishers and Agents

[Zilla1]

Does anyone in the industry know which agencies tend to have stronger links with the main publishers?

Or is it more that individual (named) agents have personal relationships with editors rather than the entire agency having an 'in' with a publisher?

I can see from the news in Publishers Weekly and the Bookseller when novelists get big ticket deals and who their agent is but I wondered if there are particular agencies who tend to have an 'in' with the big publishers?

My agent (waves if she's reading this!) worked as an editor in one of the major publishing houses for several years so I knew she had a lot of good contacts. The publishing world in the UK is very small, though, and they all know each other.