"We've been very impressed with him," Southgate said of the 21-year-old, as quoted by the Metro.
"We've tracked him for a very long time in his loan spells at Charlton, Swansea - we knew the staff there very well - at West Brom and now at Crystal Palace so in each loan he has done extremely well.
"He has started the season very well with Palace. We talked about him when we named the original squad as somebody we were keen to keep an eye on.
"I suppose it's one of the benefits of being with the Under-21s because it was an easy transition for us to bring him across."