Andrews steps up from being a set-piece coach to become the main man at Brentford and replace Thomas Frank after his departure for Tottenham,
Explaining the decision to promote from within, Giles told the club's website: “With Keith being an internal appointment and promotion, the thought process about how to replace Thomas started many years ago.
“When we replaced Dean Smith, we had Thomas lined up. While we never promised him the job, we had the idea that Thomas could potentially take over from Dean.
“It’s the same principle here. When we appoint coaches, we always have an idea about whether they could potentially step up.
“When we became aware that Tottenham were interested in Thomas, we had a more detailed process, speaking to our staff but also arranging to speak with some people externally.
“That process started before Thomas had even formally left because we knew the direction of travel.”
Fits our culture well
On Andrews' qualities, he also explained: “Keith is a very, very good person. He has good values and fits our culture well. He gets on with everyone, he’s very open and he’s a learner.
“He joined us a year ago as set-piece coach because he wanted a new experience. He wanted to be at our club and to learn. That says a lot about him.
“He’s also covered many other parts of the game so he’s well qualified to do the job.”