The 29-year-old Nottinghamshire bowler was a surprise choice to replace his injured county colleague Ryan Sidebottom in the England side for the second Test against South Africa at Headingley on Friday.
Although born in Grimsby, northern England, Pattinson grew up in Melbourne and his Australia-born younger brother, James, has represented the Australia Under-19 team.
Cricket officials from his home state Victoria admitted surprise that Pattinson, who is contracted with Cricket Victoria, was not an Australian citizen and even eligible to play for England.
"We didn't realise he wasn't an Australian citizen and didn't have an Australian passport," Victorian general manager of cricket operations Shaun Graf said.
"He actually only had a British passport and hence when he came home from playing overseas a couple of times he needed to get a visa which is a little bit strange."
Pattinson's opportunity only evolved when Cricket Victoria received an offer to play with Nottinghamshire, Graf said.
Former Australian swing bowler Damien Fleming said he was shocked when he heard that Pattinson, a roof-tiler by trade, was making his debut for England two seasons after playing his first match for Victoria.
"It's unbelievable. I don't reckon he'll be doing any roof-tiling for a while," Fleming told The Age newspaper.
"He's got good attributes. He's a pretty strong fellow, he's nice and tall, and he gets really good bounce.
"He has a pretty uncomplicated action, so not much can go wrong, and he's a ripping bloke, so I don't think temperament would be an issue either."
Former Victorian all-rounder Brendan McArdle, who helped set Pattinson up initially with clubs in Yorkshire, was another surprised by his sudden elevation.
"It was in his mind to play county cricket, but we never thought England," McArdle said.
"He's so Australian in his ways you would never believe it. He's a competitive bugger."
If Pattinson kept his English origins quiet while he was playing in Australia, it wasn't for fear of being sledged.
"People wouldn't have a go at Darren," his former Dandenong club coach Warren Ayres said. "He's pretty big and pretty wild."