Van den Berg was left frustrated by limited game time at the Anfield club over the past couple of years.
He decided to call time on his stay with the Reds, moving to London and the Bees instead.
He stated over the weekend: “I was very clear from the start that I wanted to play this season.
“At Liverpool you have two of the best centre-backs in the world at the moment. To me it was the right moment to leave, I’m at the age when I needed to play.
“I’ve done it for many years going out on loan. It was time for me to make the permanent move and establish myself as a Premier League player and that’s what I’m doing so far. I made the right decision (but) still a long way to go.”
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