The Welsh winger, 21, is now on the verge of a dream move to Manchester United – the second time in five months he’s been in line to leave.
The first came when the Swans agreed to sell to promotion-chasing Leeds. James made the trip to Yorkshire and was poised to sign only for Swansea to veto it at the 11th hour.
That’s unlikely to happen again, though, with United ready to pay £25million to get their man.
“If they are offered in excess of £20million for Daniel, then it’s difficult to turn down,” Hartson told the Mirror.
“It would also be hard to deny the boy the chance to play for the likes of Manchester United.
“He was very close to going to Leeds on the final day of the January transfer window for £10m.
“But I believe Swansea pulled the plug on the deal at the last minute because they thought, at that price, it was a steal.
“The transfer was almost over the line. I believe his parents were at Elland Road with the lad, but Swansea then told Leeds the deal was off.
“It wasn’t very nice for Daniel because he had probably pinned his hopes on joining Leeds, who then looked like they were on their way to the Premier League.
“The way things have developed could be better for both Swansea and the player.
“From the club’s point of view, the transfer fee will at least be doubled – while Daniel could join one of the Premier League’s top clubs.
“He is a special talent and very, very quick. He runs with the ball, can beat a man and can finish – I watched him score for Wales in only his second game, the winning goal against Slovakia.
“Ryan Giggs, the Wales manager, obviously believes in him. That was fantastic for his confidence.”
James’ playing style – and nationality – has earned him comparisons with Welsh flyer Gareth Bale.
They are flattering comments but ones Hartson think are wrong.
“If you have a good desire and work ethic to improve, then, with the top coaches and being surrounded by top-class players, you will,” he said.
“But it’s unfair to start comparing him with Gareth Bale, just as it was when Gareth was compared to Ryan Giggs when he first broke into the Wales team.
“Ryan had 13 Premier League winners medals, while Gareth was just starting out.
“Now it’s Gareth who has four Champions League winners’ medals – and Daniel is just in his infancy. I wouldn’t want to put any added pressure on him.
“He has a good family around him. He seems a level-headed lad and I think he will thrive.”