Kevin Schade proved the matchwinner for the Bees at London stadium.
Frank said, "It was a very good win. It was a very impressive first half; a really, really top-level and complete control and dominance.
“The only complaint was that we weren’t out of sight: we should have been at least 3-0 up, two disallowed goals, one marginal offside, Kevin (Schade) hit the post, six or seven big moments, like (Yoane) Wissa’s where he was through but couldn’t quite get a connection.
“The second half was more even but we were fairly in control, even though we had to defend a bit more. We gave a good chance to (Mohammed) Kudus but, other than that, there was no real threat.
“Big credit to the team for digging in - I would’ve liked the second goal to kill the game, but we got over the line with a 1-0 and a good clean sheet.”