SAM Allardyce has urged Wanderers to back Gary Megson in the transfer market.

The former Bolton manager has been impressed by his old club’s resurgence this season.

But Big Sam says the Wanderers boss must be given funds to further strengthen the squad when the window reopens in January – or face the consequences.

“The ever-growing problem every manager has is persuading his board to invest more and more money,” said Allardyce, who left the Reebok for an ill-fated spell in charge of Newcastle in May 2007.

“If you’re going to sustain the success then the only way you can do that is by buying players that are better than the ones you have already got.

“If you can’t compete on that level then, ultimately, you will fail.”

Allardyce, who is red-hot favourite to take charge at Sunderland following Roy Keane’s departure, believes Megson has turned it around after last season’s battle with the drop.

But the ex-Whites chief admits he was shocked at the club’s plight after he left.

“I don’t know why they struggled because it was a hugely successful operation that I built there, but that’s no longer the case,” he said.

“That’s completely changed from every aspect now. Rebuilding takes time and that’s happened on and off the field now.

“It’s difficult for Bolton Wanderers based on the size of the transfer fees today, but they had a go and spent a few bob and are reaping the rewards from that at the minute.”

He added: “Like everybody else, you have to ride out the pressure that comes on you with a few bad results, and the only way to do that is by winning football matches.

“Gary lived with those pressures and the players have, and they’ve turned it around recently.

“I think now they’re in a good mid-table position and they will try and build from there as long as, every manager will say, he can keep his best players fit.”

Allardyce also revealed his regret at the lack of homegrown talent the club has produced during his eight years in charge at the Reebok.

The club have just spent £3million on a new Academy, but he thinks the lack of investment in the youth system in the past has hindered the development of new blood.

He added: “The other avenue that has been disappointing is that the club hasn’t developed their own players enough.

“That was always a big thing for me that it didn’t materialise in the eight years I was there, and that should have been one of the main streams that they focused on. But, unfortunately, they didn’t.

“At the end of the day it’s about investment again and, of course, you have to balance the books at every club and it didn’t quite get as much as it deserved really.”

Allardyce lasted just 24 games at St James’ Park before being sacked on January 9.

But the 54-year-old is desperate to return to management – and would love it to be at Sunderland.

“There’s been no official contact but I know what a great club it is,” he said. “I’ve worked there twice before; once as a player and once as a coach with Peter Reid, so I know what it needs but we’ll just have to wait and see.

“There’s been one or two positions I’ve talked about but I haven’t felt it was right for me to go at that particular time or for whatever reason.

“But I really feel I’m ready now. After almost 16 years on the trot in management, I needed a break and the break had to be long enough for me to come back with all guns blazing, and it has been now.”