Hi everyone.
I am British. I grew up in southern England, about 150 miles from where Robert Irvine is from.
His accent is not a real accent. No-one in England has this accent.
His accent must be made up. He seems to speak about 2/3 with a British accent then throws in a lot of American pronunciations to sound glamorous. The way he says “Restaurant” is a typical example. The aunt at the end of the word is a very short, closed o sound in UK English, but he pronounces it the more open, longer American way. Yet he doesn’t do any of the American r effect with the second “r”, like Americans do, e.g. the way you say “hear”, “fear”, “are” etc. where Americans pronounce the “r” but Brits do not.
I believe that in the US the British accent is seen as “quaint” or “cute”? Well in the UK, the American accent is seen as “cool”, “glamorous”, “like movie stars”. I think this is why he puts on this accent - he wants to look more glamorous or exotic.
I can tell you 100% that his accent does not come from anywhere. I found this website, and created my username, just so that I could post on here and comment how annoying and fictional his accent is! I found this website by googling “Robert Irvine accent” because I was on holiday in the US recently and watched a programme with him in it and could not fathom his bizarre accent. So in this case the claim “Brits are good at pinpointing an accent” does not apply because it is not a real accent.
FYI, despite being “English” (although his accent suggests he is in serious denial about his heritage), he is completely unheard of in the UK. In the UK you can go up to anyone in the street and say the name Gordon Ramsay and everyone has heard of him. Robert Schwarzenegger-Irvine is completely unknown in the UK. I guess that’s why he’s gone across the pond to reinvent his career … and his accent.