Durham, 2013. Ryan Harris, newish ball in hand, fizzes it down towards the top of Joe Root's off stump. It takes a little wobble through the air, hits one side of the seam, and darts perfectly away to beat a flummoxed Root and hit the outside of the off stump. It's a cracker, but almost completely accidental, as Harris admits later to Ian Ward.

Have you bowled a better delivery than this?

"Probably not, but I don't try to do it, I just try to put it in the right spots and let the ball and the wicket do the rest. I'm aiming for the top of off, it doesn't always go there but it's great to get one in the right area now and then."

The seam's just wobbling, deliberate?

"No, not really. When I went off after our spell I said to our analyst 'how's my seam' and he said it was a bit wobbly and I wasn't very happy with it. So I'm trying to get it nice and straight, but if it comes out like that it's natural variation."

Later that same year, Harris would bowl a far more famous delivery to Alastair Cook, albeit with the seam so straight that it swings after pitching to hit the top of off. England, victorious at home, are beaten out of sight Down Under. But they still possessed a weapon, particularly at home, that Australia's bowlers had not yet truly grasped: Harris's wobbly seam at Durham could be done deliberately, and cause mayhem.

James Anderson and Stuart Broad had, in fact, been bowling this type of delivery for years - Anderson's series-winning haul of 24 wickets on the 2010-11 featured the wobble-seam prominently. Ironically, he'd learned of it from watching Stuart Clark in the Ashes whitewash four years previously, but after watching Mohammad Asif's impact in England in 2010, he went off to the nets with David Saker, then England's bowling coach, and set about mastering a skill that wasn't actually all that complicated.

For Australia, there seemed an initial reluctance to divert from trying to land the seam as straight as possible. The chief advocate for the method has been Peter Siddle, helped by the advice of Saker, Broad and Alastair Cook, via their time together in Victoria, Nottinghamshire and Essex respectively. Siddle, though, was on the outer in 2015, not playing until the Ashes had already gone to England.

"David Saker who I've spent a lot of time with and he's mentored me for a long time, talking to him even when he was still England coach around how they went about it," Siddle told ESPNcricinfo. "You mix that in a little bit with having that time with Broady and chatting to him first-hand, rather than just watching him bowl it, how he holds it, how it feels, how to release it. From then it's just about finding your way, what feels good for you and it's just something that grew and adapted over time.

"Even in the last couple of years playing with Alastair Cook, and this is my fourth series over here, so in that time you do watch the opposition and see how they go about things and what they do with the ball. It is something that in the last couple of years I've got better at, and had a lot more success with it."

Repeatedly, Siddle was the most challenging opponent for Australia's batsmen in the nets in 2015, but there was an element missing: collective unity about which plans to follow, how and when. There was, to some extent, variation, until this January, when there was a very public disagreement between the pacemen and Tim Paine about how to bowl on day one at the SCG against India. A unified plan to strangle England, and a unified method of how to use the Dukes ball, was required.

I thought Peter Siddle was almost the bowler of the first Ashes Test - Justin Langer Getty Images

The penny dropped in Southampton, with 25 Australian cricketers plus just as many support staff squeezed into the Hilton at the Rose Bowl. Among many meetings the use of a scrambled seam stock ball, with straight seam swingers for variation on a rigorous top-of-the-off stump length - plus the occasional bouncer - crystallised as the only way forward.

For Siddle, this meant being as much a coach and mentor to the other bowlers as a competitor for one of bowling spots in each Test team.

"It's a pretty simple game-plan, but it takes everyone to buy into it," he said. "It's good to see the boys having a crack at it and getting some success, because on wickets over here even when they flatten out, they have still got that little tinge of grass scattered around so they still tend to offer a little bit.

"I think it's showed for both teams that the team that have stuck in there and been patient enough, you've been able to get the rewards."

Cummins, Siddle and James Pattinson used the method to good effect at Edgbaston, before Hazlewood subbed in at Lord's and raised the level a notch further. At Headingley, Pattinson returned, and Australia razed the hosts for 67. And even when Ben Stokes conjured a second-innings miracle on a pitch that flattened out into the easiest batting surface of the series, there was plenty of reason to stay the course.

The last piece of the puzzle was Mitchell Starc, who was perhaps the hardest sell. For nine years, he had been a Test cricketer committed to seeking swing, and often benefiting enormously from doing so at his great pace. But through many net sessions, plus tour games at Worcester and Derby, he too learned to get the seam wobbling, and at Old Trafford the variation was critically important: Jonny Bairstow was bowled by the inswing variation in the first innings, then Stokes nicked off to a wobble seamer. Starc had adapted.

"It's been a series where there hasn't been as much swing, even though this ball they went back to the old Dukes ball because the new one doesn't quite seam as much," Siddle said.

"That brings the wobble back into it, but that is exciting to see for Starcy. I bowled loads with him early on in the series in the nets and he was just asking questions, having a go at it, and then trying to see what would work for him.

"At times it didn't feel right, and for a bloke that naturally keeps the seam up to swing it, it's going to feel very awkward because it's just not natural. But to see him bowl some of those balls and have the success that he did I think it showed that actually listening to what is needed in the conditions sometimes going away from what you normally do, having that success has given the guys a lot of confidence."

Compared to 2013 and 2015, Australia have swung the ball far less, and seamed it far more. They have moved the ball off the pitch even more than England.

Amid the adaptation, a revelation too. Australia's faster bowlers, Starc and Cummins in particular, are able to get additional variations from wobble seam that Anderson, Broad and Siddle cannot.

"This is my fourth series over here, so in that time you do watch the opposition and see how they go about things and what they do with the ball."

"I think like the scattered grass, sometimes it's there, sometimes it's not," Siddle said. "If the quicker bowlers are getting it off the little bit of grass patches that are there, it does sometimes look to shoot on. Sometimes they do and it doesn't bounce as much.

"Jimmy and Broady and I, they'll seam and stand up even though I'm a lot shorter and Jimmy's a bit shorter, but that extra pace it skids on and probably keeps a bit lower. That's all a part of England, the natural variation. The big thing too is bowling the right length with it. You can see over here you get a lot of plays and misses, which is pretty natural, but the fuller you are, making them have to 100% commit to the ball, you get the breakthroughs. LBWs and bowleds, there's probably been a higher number of that than just caught behind the wicket."

So a method first glimpsed in use by an Australian, perfected by a Pakistani, then co-opted by England, found its way back where it started, in the nick of time for the 2019 Ashes. "The teams that have had the most success are the teams where everyone buys in, you bowl in the partnerships at both ends, you build pressure, and you get the rewards," Siddle said.

"I think that's what's been so strong about this group, not just the fact there's six strong, quality fast bowlers in the group, but i think when blokes have come in and out of the team, they've been able to fit straight in, stick to the plan and have the success."

Old Trafford, 2019. Pat Cummins, brand new ball in hand, fizzes it down towards the top of Root's off stump. It takes a little wobble through the air, hits one side of the seam, and darts perfectly away to beat a flummoxed Root and hit the outside of the off stump. It's a cracker of a ball, and it is almost completely deliberate.