Harris, who took two wickets in an over on day one of the second Investec Test at Lord's where England finished on 289 for seven, first played at HQ for Sussex in 2008.
His four wickets on debut back then for the champions against the MCC, before he had played for his native country, immediately convinced his county employers they had made a shrewd investment.
Disappointment was swiftly to follow for them, though - when Queensland moved in to sign Harris from South Australia, on condition he committed himself to the Baggy Green.
The pace bowler was therefore dramatically pulled out on the morning of his next scheduled match for Sussex, against Hampshire at Southampton, after deciding - despite the British passport he held because his father was born in Leicester - he could not play as a domestic player after all in this country.
"I travelled here to play a little bit, and having an English passport made it a bit easier," the 33-year-old said after a see-saw day at HQ.
"Dad moved over to Australia when he was 10 or 11, so he was brought up an Aussie and brought me and my brother up as Aussies."
Even so, Harris had the option to consider a possible future for England - almost a year before he made his Australia one-day international debut.
He is now taking part in his second successive Ashes series, but still recalls his 2008 rethink and the moment he had to make his intentions clear as a potential international cricketer.
Speaking in the England and Wales Cricket Board offices, he said: "Last time I was in this building I had a meeting with Mike Gatting about that passport.
"It was a messy situation ... I had a really good offer for Queensland that came through at the time, and that's where I thought I might have one last crack at trying to play for Australia.
"Obviously, it was the right move."
He has made plenty more since, but there was one false one too from Australia on Thursday - when Harris' fellow seamer Peter Siddle paid dearly for over-stepping the crease for the delivery which bowled Jonny Bairstow for 21.
The batsman went on to share a stand of 144 with England centurion Ian Bell, after a no-ball was called.
Harris said: "(Coach) Darren (Lehmann) is quite strict on that with us in the nets ... once we're off our long runs, we're not allowed to go over.
"There's no excuse for it. The line is there for a reason.
"It's not acceptable. It cost us a lot of runs today, and potentially ... it could cost the Ashes.
"Darren wasn't very happy. You just can't afford to (have to) take 11 wickets, or 12 wickets. It's as simple as that.
"It was probably the only one he bowled, but funny how it happened to be a wicket. That's how the game works."
As for Bell, scoring his third hundred in successive Ashes Tests, Harris admits Australia were hoping he might be vulnerable this summer.
"We thought he was struggling coming into this series - he hadn't made a lot of runs," he said.
The tourists have proved wide of the mark there, and Harris reports they are now planning to try to copy some of Bell's attributes themselves.
"We spoke about our batters modelling themselves on him, and taking their time," he said.