And indeed “herbs” which is pronounced " 'erbs" in the US and “herbs” in the UK (because, as Eddie Izard said, “it has a fucking ‘h’ in it” 
)
Robert Irvine’s accent is definitely Welsh. From the Glamorgan, possibly Vale of Glamorgan area. There is a large dose of Royal Navy and USA accent in the mix too.
Hope that helps.
That’s my guess too - some sort of Creole accent that may have started out somewhere in Britain, but then got a fair dose of Navy and a fair dose of US speech.
I once dated a British girl who was Scottish by ethnicity (parents and family were Scots), but she herself had grown up in Hampshire, and sounded about as English as could be.
Every time she went back to visit, she complained about how her family, friends and acquaintances said that she sounds “American”, which always made me laugh, as she sounded clearly and overwhelmingly English to anyone here in the US.