With West Ham in the process of recalling him early from his loan spell at Millwall on Monday afternoon, Glenn explains: "I wanted to leave him at Millwall for a third month but circumstances haven't allowed me to.
"At Old Trafford on Saturday we used young Anton Ferdinand on the bench, and he is only 17, not 18 until next summer.
"He is a player of huge promise and potential, but he is not really ready to be as close to the first team as on the bench.
And, with the injuries that have mounted up - we have now got Edouard Cisse out with Chicken Pox that will rule him out for anything between 10 to 14 days - I have had to bring Glen back.
"I have also brought Grant McCann back from Cheltenham Town as well and they are both going to be in training with us tomorrow.
"We are delighted with the opportunity that Millwall have given Glen. I think he has had eight starts in the first division, doing exceptionally well.
"I know Mark McGhee has been pleased with him, and it has worked two ways, because I have been pleased that he has now been blooded at a higher standard.
"I know he made a good impression with all the supporters and players alike at Millwall, so it has been a useful exercise.
"With the current size of our squad being stretched beyond the limit I expect Glen Johnson could very easily be on the bench in the next few games.
"We see Glen as making right-back his position, but at the moment Sebastien Schemmel has got the shirt and he is obviously a much more experienced player.
"But Glen can also play as a central defender and he is pretty versatile. It will be good to have him back to see how much being with Milwall's first team squad every day has improved him."
Grant McCann is also coming back to the club, though he would only have figured in one more game as he was suspended for three matches following a sending off.
Leon Britton has been allowed to go to Swansea City for a month, though, and Glenn adds: "Grant has done very well at Cheltenham for the second time but, with Leon going out on loan, now was the right time to bring him back.
"He is suspended for three games and can't play for anyone until after Boxing Day, so he will stay with us until we feel we can let him out on loan again.
"I decided to let Leon go to Swansea as he has been very patient waiting for the opportunity to go out on loan. They wanted to give him the chance of first team football and I didn't want to deny young Leon that.
"He is a super professional and I wouldn't have needed him over the Christmas period."
As for Brent Rahim, currently on loan from Levski Sofia until the end of the month, Glenn says: "I need to talk to Brent, probably this week, but no decision has been made.
"He is playing in the reserves again on Tuesday night but he is one I need to talk to about his future in the next few days."
Edouard Cisse's illness is something of a concern to Glenn, who adds: "Edouard's son has had Chicken Pox in the last seven or 10 days and Edouard himself didn't realise he hadn't had it.
"You only get it once in your life, but he didn't have the virus as a child, and now he has picked it up he needs to stay away from the club for the next seven days.
"Depending on how severe the dose is - and it can affect adults in a bad way - will determine when he is going to be available again.
"He would have been fit for the Bolton game because the hamstring which ruled him out at the weekend was only a very slight one."
It has left Glenn cursing his luck and he concludes: "You wonder why these things are happening to us at the moment."