The youngster trained with the Glovers this week.
Johnson said: "He's certainly one to keep an eye on. We know his personality and he's a good lad."
Johnson explained why he'd turned down the chance to loan the former England Under-20 man.
"I thought he did very well, but unfortunately his trip was organised on the Wednesday and Thursday and by the time he came down we had injury problems with our keeper and defender and I had to bring in two loans, which gave me six."
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