Henson had been prepared to retire when his agent was told by the Blues – before the drink-related incident on a Flybe flight from Glasgow in April – that he had no future at the club.
The 30-year-old had joined the Welsh region after unsuccessful stints with Saracens and Toulon, and he felt it would have been “embarrassing” to sign with a fourth club in under two years.
But when the Blues terminated his contract, Henson knew he could not end his career on such a sour note and he accepted the offer from Aviva Premiership new-boys London Welsh.
“I want another chance to put things right because I thought that was it,” Henson said.
“It was going to be my last club. I was made well aware they weren’t going to sign me on. That was demoralising.
“If you watch that last game [against Glasgow] where I was brought on as a wing – that sums up the way things were at the club. It was tough.
“I couldn’t move on to another club. It was starting to get embarrassing. I was more or less finished then, rugby-wise.
“The writing was on the wall before then and they took their opportunity to strike. I fell into that trap really.
“In a way, if there’s anything good to come out of it [being sacked], it was that I knew things couldn’t end like that.
“I had to bite the bullet and sign again for another club and try and put things right.
“I just have to make sure I stay on the straight and narrow and play the best I can.”
Henson was given his “last chance” by his former Ospreys coach Lyn Jones, arguably the one man who could get the best out of the Wales and Lions international. Earlier this week, Jones described Henson’s recent past as a period of “fannying around” – and Henson understands the perception.
In 2009, he took an 18-month sabbatical from rugby and became a reality television star before being drummed out of Toulon and Cardiff Blues for disciplinary reasons.
But Henson has convinced Jones he is serious about rugby and about recapturing the form that helped Wales win Grand Slam titles in 2005 and 2008.
In return, Henson has been placed at the heart of the London Welsh operation. He will play at fly-half for the Exiles and he already feels a key and valued member of the squad.
“I played my best rugby under Lyn in 2003-2004. I am looking to try and recapture that. I’m totally focused on rugby,” Henson said. “I have hardly played, have I? I couldn’t help it. My body let me down a little bit.
“I took my time out and it has been a rough ride trying to get back in. I am just hoping I get a fair chance here.
“I have got a better feel here. I am involved, which is nice. It is tough when you are not.
“I really just want to play rugby. This is my last chance and I want to go out playing 10.
“Fly-half is the position I most enjoy. I have a bit of self-doubt about whether I can play there because it has been so long.
“I am looking forward to seeing how it goes.”
Henson also recognises exactly where he stands on the international front and, on this occasion, he has no illusions about walking straight back into the Wales squad.
In 2010, Henson drew criticism from his team-mates for modelling the new Wales kit before he had even returned to rugby from his sabbatical.