"I saw it as a great challenge to come over here to play for a great club.
"Obviously I had to have a discussion with the family as well because I moved back to Sweden in the summer so I had to have a chat with them and see how they felt about coming over and as soon as that was clear with the family then there was no problem.
"When I was in Scotland with Celtic, me and my family were very settled and that was part of the reason we didn't come down here at the time.
"Also we had a good team at Celtic as well. But now when I heard about this loan deal with Manchester United this was a chance I couldn't say no to.
"I'm 35 years old and I don't think I'll get another chance to join such a big club. But I'm not just here to enjoy myself. I obviously understand how important all of this is so there's no question it's an important time and I'm fully aware of that.
"Obviously the gaffer decides where and when he's going to play me.
"For me that's (being a sub) never been a problem, it's not a problem for me.
"I know what I'm here for and hopefully I can do it. What I can do is train as good as possible and whenever I get a chance to play, play as good as possible.
"That's what I can do - I try to always win and when I train I do 100 per cent, that's all I really can do.
"I think whenever you are in the penalty area, you need to finish as quickly as possible and that's no different from playing in Sweden or somewhere else.
"When you get the chance, it's important to take it as quick as possible, and when you need to be calm, be calm. Hopefully I can do that here as well.
"I'm really looking forward to this. I'm going to take one game at a time and see what's happening."
When asked if there would be an extension he said:
"Everything is possible."
"We need an experience player like Henrik and as soon as his name was mentioned as a possibility for January I thought it was a great idea.
"OK, he maybe only here for a short period, but that maybe the most important short period in the club's season. Hopefully it is.
"The most important thing about Henrik is that he has a tremendous goal instinct and I think that is part of his character that has always been there and is a great addition to our club," said Ferguson, who saw United's lead at the top of the Premiership cut to two points last weekend after his side proved profligate in losing 1-0 at West Ham.
"That is the problem, seeing him go in March, but you hope that by then he will have done enough to keep us at the sharp end of the competition," said Ferguson.
"We will be sorry for that day to come but, in fairness to Helsingborg, we wouldn't want to intrude on their ambitions. We needed an experienced player. He may be here for a short period but that may be the most important short period in this club's season.
"Our standard of play has been very good but we have been missing some chances, like in Sunday's match. Hopefully the experience of Henrik and Ole Gunnar [Solskjaer] will make it decisive for us.
"When we announced it, a few of the players came to me and said: 'That was a good one, where did you pull that one from?' They were surprised by the secrecy that surrounded it. It has come at a good time. It looks like the championship race is going to go the whole road and people like Henrik could really help that."
However, once Larsson's loan deal expires on March 12, the temptation to hang on to him with a potentially decisive fixture at Stamford Bridge a little over a month away would be intense. "But you hope that by then he will have done enough to keep us at the sharp end of the competition," Ferguson said. "We will be sorry for that day to come but in fairness to Helsingborgs, who have been very good, we wouldn't want to intrude on their ambitions."