Moeen Ali has paid tribute to the "amazing" Saqlain Mushtag for his role in helping the England all-rounder enjoy a record-breaking Test series against South Africa.

Ali, a 30-year-old off-spinner and left-handed batsman, became the first man in cricket history to score more than 250 runs and take 25 wickets in a four-match Test series during the course of England's 3-1 victory over the Proteas.

Ali has often been regarded, even by himself, as a "second spinner" when the likes of Hampshire left-armer Liam Dawson have been in the England side.

But under the guidance of England spin-bowling coach Saqlain, a former Pakistan off-spinner and star of a Surrey side that won English County Championship titles at the turn of the century, Ali's bowling has improved markedly.

"Saqqy has been amazing for me in terms of helping with my fields, helping me understand my bowling a lot more than I had done previously — and I think that has been the biggest difference," said Ali after bowling England to a 177-run win in the fourth Test at Old Trafford with more than a day to spare on Monday.

"Little things like that can make a big difference," explained Ali, who ended the match with two wickets in two balls for an innings return of five for 69 after finishing England's victory in the third Test at The Oval with a hat- trick.

"Before, I just bowled, (and) didn't really think too much," added Ali, who started the series with a 10-wicket haul in England's first Test win at Lord's.

"I let the captain set the field. I would say I set the field a lot more throughout this series."

The South Africa series saw Ali, who showed his batting class with an unbeaten 75 not out in England's second innings at Old Trafford, cement his position of fourth in the International Cricket Council rankings for Test all-rounders.

"I feel a lot more confident in my ability," he said.

"I feel like it was building… I had been batting well over the last year, and the bowling was coming."

Joe Root, whose first series as England captain ended with a decisive victory, has been delighted by Worcestershire star Ali's progress.

"He is definitely improving all the time," said Root.

"I hope it's not just a one-off series, and he can go on now and do it again and again."