Richardson left for Old Trafford as a youngster but Glenn says:
"We would have liked to have kept Kieran Richardson, it goes without saying; he was very highly rated by our people and we did everything we could to keep him, but we couldn't change his mind.
"He decided to try and make a career for himself at Old Trafford which he is already doing - the very fact that he is touching base with the United first team squad, having already made his debut, tells you that.
"If he had with us he would already have been playing in our first team.
"Unfortunately, you do lose a few, but on the flip side of the coin you also gain a few.
"That side of it is swings and roundabouts; the important thing is we gain a few more than we lose."
Looking at preparations for the weekend's big clash, he says there is no depression around his players:
"I always come off the training ground at Chadwell Heath encouraged by what I have seen from the players," he says.
"Unfortunately this year, with our lack of a home record, it is infuriating and mystifying that we haven't taken the quality of those practices into our games at Upton Park.
"That is what we will be looking to do on Sunday and we have got to look forward to the game; Manchester United is a special game for any player because they have been the benchmark over the past 10 years or more for everybody else.
"Only Arsenal or Liverpool have got close to them and occasionally bettered them in terms of winning the Premiership.
"The motivation should be absolutely there without having to go and look for it; if you have got anything about you as a person, you should relish a challenge.
"Most human beings do, and when you are a professional footballer there is no bigger challenge than testing your ability against that of Manchester United."
As for the reasons for the poor home form this year, he admits:
"We are all looking for the answer and trying different things; we keep searching, keep looking, and keep working hard until we find a solution.
"There is one, we have got to find it, and quite often you will find that the solution comes from within.
"But that first win at home will breed the confidence which is hard to find at the moment.
"But they showed in the second half against Leeds that they can come out and play in a fantastic manner - and the trouble is, those four horrible non-defended goals we conceded last week also disguised the fact that we actually played well ourselves for periods of the second half.
"We created chances in the first half and the first time Leeds got in the box was for their first goal after 11 and a half minutes.
"We had carried the game well to Leeds, we were in the ascendancy, and it was only a few seconds earlier after Paolo Di Canio's quick free kick for Trevor Sinclair to head over that gave us a goal scoring opportunity.
"From that goal kick it was completely unacceptable in the manner that we lost the goal.
"Individual errors are the biggest problem and as motivated and driven and competitive as you want them to be when those mistakes are made it takes an awful lot of character to keep going without becoming demoralised.
"It showed incredible effort to pull the game round, and quite honestly they didn't get what they deserved as a team in the second half, because if we had we would have taken at least a point - and you could have argued that on another day we would have got all three points.
"And if you had suggested that at half time you would have been laughed out of the ground - or thrown out!
"So they showed the supporters what they are capable of, that they are right behind the club, and that they want to put it right.
"And, I suppose from my point of view, at this particular time I think they showed they really want to play for me as well.
"Of course I am angry and annoyed with errors that only belong on Hackney Marshes - but they are a genuine group of players.
"The people that are concerned with the mistakes are deeply upset but they are a tight unit and they want to put this situation right once and for all.
"It can't possibly be put right overnight; the situation we find ourselves in can't be overturned in one or two weeks.
"It needs strong characters now over the next three or four months to pull us away from where we don't want to be.
"We are now entering into a battle, maybe a war, that we have to win.
"I have an immense amount of confidence in that squad, though I would like it to be better.
"I think that confidence is mutual and between us we have to get out of this situation - and make sure it doesn't happen again.
"But first things first - you can only address one thing at a time."
Glenn knows only too well that the home form is putting pressure on the away form and he adds:
"Because it hasn't happened in any way, shape, or form the away form has to be good.
"I have always maintained that you have to take at least a point a game away and last year and we only took 13 last year from 19 with 40 points at home.
"We have taken nine away points so far this year so we need another 10 points away, in my opinion; the rest of the points have got to be found at home."
As for the spat earlier in the week following the appearance of criticism of Paolo Di Canio by Julian Dicks, Glenn says:
"I would rather not comment on that; the only point I made was that Julian always played with an incredible amount off commitment and a huge degree of ability as well.
"It is that type of fighting spirit that we need to keep because there were long periods in the Leeds game when we weren't gifting them goals when we showed the fighting spirit required.
"Other things that were said I wouldn't want to comment on; I think enough has been said and enough points have been proved to now let it rest."
Glenn insists that there were plenty of positives on Sunday, and adds:
"There were plenty of players that played exceptionally well; Trevor gave a brave performance, it goes without saying that Paolo was inspired, Michael played with courage, Eduoard who came on, and Sebastien who looks to be back to full fitness.
"Hopefully he will now set his season alight, and he is completely over the foot injury which I think has restricted him at times this year.
"And because he is immensely happy with his foot he showed incredible energy and desire against Leeds when he came on.
"Michael was always wanting the ball and was always probing, and Joe had times when he was a handful running with the ball.
"Jermain is working extremely hard; he is getting little change at the moment but he has got a tough mentality and he is just waiting for those few opportunities to come his way - which he deserves.
"And we mustn't forget Nigel Winterburn who came back in and played like we know Nigel can; he has got an amazing will to win and you know why he has got a stack of medals and honours.
"I think Nigel and Sebastien will be looking forward to the game."