But the world number three then birdied the par-five 16th as Knox three-putted and, after lipping out for birdie on the 17th, fired a stunning approach from 252 yards to within three feet of the hole on the 18th for a closing eagle.

253 yards.

The shot of a champion. https://t.co/7EpcJKAbWH

— DP World Tour (@DPWorldTour) May 22, 2016

The resulting 69 meant McIlroy finished three shots clear of Knox and Wales' Bradley Dredge to claim the first prize of £515,000, which he will donate to his own foundation which hosted the tournament for the second year.

Dredge surged through the field with a 66 to secure the biggest pay-day of his career, with Knox returning a 68.

"I don't know if I can put it into words," said McIlroy, who started the week annoyed at "negative spin" on his failure to win so far this season.

"I don't really get emotional when I win but I was trying to hold back the tears on the 18th green, looking up and seeing all my friends and family.

"I don't get the chance to play in front of them very often so to play like that and to finish like that today, I will never forget it. I'd put winning your national open up there with winning a WGC, just below the majors.

"I was trying to stay as patient as I could but it's quite hard when you have 30,000 people roaring you on. The ovation I got when the ball landed on the 16th green sent shivers down my spine.

McIlroy from 271 yards. https://t.co/9uEqWgUuK9

— DP World Tour (@DPWorldTour) May 22, 2016

"I'm excited. I kept telling anyone that would listen that I was close. Maybe those last three holes is the catalyst for another great summer with three majors and everything else we have to play for with the Olympics and the Ryder Cup."

McIlroy had missed the cut in his home event for the last three years, but completed an error-free 70 in the weather-delayed third round on Sunday morning to claim a three-shot lead over Masters champion Danny Willett.

And, although Willett's challenge stalled in the final round with 13 straight pars before he collapsed to a closing 77, Knox ensured McIlroy would certainly not have things all his own way.

Using a driver borrowed from Sweden's David Lingmerth after cracking the face of his own club on Thursday, Knox missed good birdie chances on the first two holes before holing from 20 feet for eagle on the fourth and similar range for birdie on the next.

After a delay of 69 minutes following the first deluge, McIlroy edged two shots clear with a birdie on the 10th, only to three-putt the 11th and then see Knox draw level with a birdie on the 14th before play was temporarily halted again due to another spell of hailstones.

A birdie on the 15th took Knox into the lead only for McIlroy to produce a stunning approach from 270 yards to set up a two-putt birdie on the 16th, while Knox found sand off the tee and three-putted for a costly bogey.

McIlroy's birdie putt from six feet on the 17th lipped out, but it did not matter thanks to a magnificent approach to the 18th which ensured he could enjoy the walk to the green and take in the cheers of the crowd.

"It's funny, I had the exact same distance in the pro-am and JP (Fitzgerald, his caddie) tried to get me to hit a four-iron but I didn't like it," McIlroy added.

"I felt like I was trying to hit it too hard, so I dropped another ball and hit a five-wood so I had some confidence knowing what I needed to do and pulled it off perfectly."

The story behind "that shot" on the 72nd hole.https://t.co/IZhhNrPlUg

— DP World Tour (@DPWorldTour) May 22, 2016

Knox paid tribute to McIlroy's finish, adding: "I played brilliant to be honest. Obviously 16 is a huge turning point, but the shots that Rory hit in the end, he deserves to win. I shot 75 the first day and finished tied second. That's pretty good."

England's Matthew Southgate, who regained his European Tour card via the qualifying school after undergoing treatment for testicular cancer last year, carded a closing 68 to finish fourth, the best result of his career.

"It's been absolutely incredible," Southgate said.

"I wasn't even in the tournament Monday night. I was still first reserve and when I got the phone call I thought, right, this is a big opportunity.

"Something like this has been coming and I've been working really, really hard at it. I just stuck with my guns, done the stuff I've been working on in practice and it's all paid off."