Blackwell said: "We had known all about Greg for a while before we brought him here and, although he did not have a good time at Reading we knew we would be getting a player with more than just a long throw.
"His delivery and work rate on Saturday were good and we saw that he and Kyle Naughton are capable of forming a nice little link down the right.
"We are trying to get more flexibility into our play and those two are capable of switching positions and causing problems until we decide to switch again.
"It's amazing how things can turn around in this game. Last year he was on-loan for Charlton against us at the Lane and one of his throws cost us a goal - it was the other way round this time and there is no doubt that it is a useful weapon for any team."