"Gareth's a great player and because he's young he's only going to get better," said Quails.
"Obviously with quality wingers like Lee Hodges and Peter Beagrie around Gareth was not playing as much as he liked, but it's still a big loss."
Quailey has yet to accept a contract offer to stay at United, and Iron manager Brian Laws has warned the St Kitts & Nevis international striker that if he finds a replacement before he gets and answer from Quails then the offer will be withdrawn.