The 35-year-old enjoyed a City Ground renaissance under Sabri Lamouchi last season.
The Forest manager described him as “one of the best midfielders in the Championship”.
But Watson wanted to be nearer to his Beckenham home.
“It wasn’t a secret when I was up in Nottingham I was doing a bit of commuting,” he said. “I’ve got a wife and kids. Your family matter – it’s not just about the football.
“For certain reasons we weren’t able to move to Nottingham. I don’t want to go into that. But there was a reason why we couldn’t and why we never moved home.
“Throughout my career we have always moved as a family but this was a bit different.
“I had a fantastic last year at Forest even though we know as a team the end of the season never ended how we wanted.
“When Sab came in we connected. He took to me and I took to him. He got the best out of me.
“When a manager trusts a player then nine times out of 10 that is how you get the best out of them.
“But I wanted to get back home. I spoke to the gaffer Lee [Bowyer] over the summer a number of times and he sold it to me. I pushed for it last year, but it never happened.
“I’d have liked to have got it done earlier but that wasn’t the case because of the embargo. But they allowed me to come in a couple of weeks ago to train with the team, so I wasn’t months behind in terms of fitness.”
Camberwell-born Watson had never played below Championship level before making his Addicks debut as a second-half sub in the 2-0 loss at Lincoln on Sunday.
The former Crystal Palace player is only two games shy of 500 appearances.
“I’m not getting any younger but I still believe I’ve got a few more years to offer,” said Watson. “I had a couple of offers in the Championship but I turned them down. I’d set my heart on here. I was willing to wait.
“There is so much potential. It’s got all the ingredients to be the club that it once was. With the new owner that has now come in, hopefully we can get back to that.
“Looking from the outside over the last few years it has seemed a bit of a circus with everything that was going on. It needs that stability and someone to come and give the club a bit of love. Thomas [Sandgaard] looks like the guy to do that.”
Watson’s son Reggie is in Palace’s U11 team. He is watching his son train during this interview.
“He’s been there since he was U7 or U8,” said the South Londoner. “He loves football, he loves sport. Hopefully he is out there at Selhurst Park in the future. But he’s still very young and there is a long, long, long way to go.
“I was at Palace from such a young age – I made my debut at 17. They gave me the chance but then I had interest from the Premier League [joining Wigan in 2009]. It felt the perfect time to move on. I believe it was – I wouldn’t change anything I did.”
Watson, who has signed a 12-month deal at Charlton with the option of another year, has not started his coaching badges.
“I wasn’t ready to do that after the season I’d just had at Forest,” he said. “Retiring isn’t even something I’ve ever thought about.
“Within the next year or two then I’ll work out what I’ll be doing once my football career comes to an end. I want to play as long as I can – I want to go on forever. You’re a long time retired.
“Hopefully I can have a lot of success at Charlton and go out on a high.
“It’s not easy this league. You only need to look at the division to see there are some very big football clubs – Sunderland, Ipswich, Wigan and Portsmouth. It ain’t a league you just turn up and win.
“But the gaffer is looking to bring in more players now the embargo is lifted. That’s great because as a squad we need that. The standard here is already very high.
“It is a long old slog. You don’t win anything in the first 10 games, that’s for sure. The sooner we get a few more players in it will help the football club.”
Please support your local paper by making a donation
Please make cheques payable to “MSI Media Limited” and send by post to South London Press, Unit 112, 160 Bromley Road, Catford, London SE6 2NZ
Housing Secretary Robert Jenrick has encouraged everyone in the country who can afford to do so to buy a newspaper, and told the Downing Street press briefing recently: “A free country needs a free press, and the newspapers of our country are under significant financial pressure”.
So if you have enjoyed reading this story, and if you can afford to do so, we would be so grateful if you can buy our newspaper or make a donation, which will allow us to continue to bring stories like this one to you both in print and online.