The man known as “The Messiah” to Newcastle United supporters has cast himself in the role of saviour to the most tormented player in British football. As the club raised the extraordinary possibility of Joey Barton figuring in matches despite his nightly curfew at the Sporting Chance Clinic, Kevin Keegan backed the England midfield player to resume his career.

Barton is on bail over an alleged assault in Liverpool city centre in the early hours of December 27 and is receiving daily treatment at the charity established by Tony Adams, the former Arsenal captain, for troubled sportsmen. While Barton has travelled to Tyneside by helicopter this week to take part in training sessions, he is obliged to return to Hampshire by 7pm.

Keegan knows both sides of Barton’s complicated character. He was manager of Manchester City when the midfield player rose through the ranks, as he was in December 2004, when Barton poked a lit cigar in the face of Jamie Tandy, a youth-team player. City imposed a fine of six weeks’ wages – about £60,000 – on Barton, who issued a public apology.

“I had Joey at Manchester City from when he was 16 or 17,” Keegan said. “I used to watch him in the juniors. I can’t control what’s gone on with him before and I can’t control what’s going to happen in a courtroom. But the one thing I said to Joey when I spoke to him yesterday is the same thing I will say to you – he’s a Newcastle United player and I will support him 100 per cent and help him in any way I can.

“Joey has openly said he needs help and the best people who can help him are people who know him and we know him. He’s an excellent player, he can improve, he’s had some little problems, but I told him he’s got my full support. I’ve given it to him before and he’s let me down, but he’s got my support again. I’m convinced having spoken to him again that all he wants to do is play football at this club.”

Barton is due to appear at Liverpool Magistrates’ Court on March 16, until which time his movements are limited. Logistical reasons prevent him from appearing at St James’ Park for a 3pm kick-off because he would not have time to return south, but there is slim chance of him playing in away games. Given his bail conditions, it would represent a risky strategy, but Keegan is hardly adverse to that.

“Joey comes up and trains, but the practicalities are that he can’t play in Newcastle,” Chris Mort, the club’s chairman and a lawyer, said. “What we said to Sam Allardyce when it all happened is that we wanted him to make the judgment on how we take this forward. We said the same to Kevin and he said, ‘Look, let me sit down with Joey and talk with him.’ It’s something that we’ll do together.

“His bail conditions do not say, ‘Joey cannot play football’. They put timing constraints on him. It’s always going to be the manager’s decision who plays, but if we were playing in London in the middle of the afternoon, perhaps he could play for Newcastle. Could he play at Arsenal [this month]? Possibly, if you’re willing to wait outside and get him home on time. It will be Kevin’s decision.”

Mort also revealed that Newcastle were studying the viability of increasing the capacity of their stadium to 60,000 from 52,387. The previous regime submitted plans to the city council about building a third tier on to the Gallowgate End. “It’s something we’ve been looking at since we took over the club and we’ll continually assess whether that’s a good or bad thing to do,” Mort said.