It has been more than four years since Prince Harry stepped down as a senior working royal and bid farewell to London in favour of sunnier days in Montecito with his wife, Meghan Markle.
Although he was educated at Eton and was taught to speak the King's English, it appears he is now losing his original accent.
The Duke of Sussex, 40, has previously expressed his joy at living in the States with his children Archie, five and Lilibet, three, describing his life in America as 'amazing'.
He even admitted that he 'loves every single day', adding that he has thought about becoming a US citizen, in an interview with Good Morning America in February.
The Duchess of Sussex, 43, is a Californian and has remained in the state just an hour and a half's drive from where she was born in Los Angeles.
Fans now believe that Harry has adopted Meghan's American accent and sayings, after a video emerged of him getting a fake tattoo earlier this week.
The two-minute long skit with musician Jelly Roll, filmed at New York tattoo parlour East Side Ink, saw people pointing out that he has now gone Cali cool.
One wrote: 'He totally has an American accent now,' while another penned: 'Prince Harry's British accent sounds more diluted to make way for the American accent.'
He then used several American mannerisms, calling the tattoo artist 'dude' and saying 'That [tattoo] feels big man'
Another said: 'It sounds like Prince Harry is losing his British accent.'
The clip - which was filmed to promote The Invictus Games - sees the Duke say the American term 'Screw it, let's do it,' to Jelly Roll.
He then used several American mannerisms, calling the tattoo artist 'dude' and saying 'That [tattoo] feels big man.'
The royal then exclaimed: 'You put your name on my neck,' raising his voice at the end of the sentence, which is commonly what US speakers tend to do.
He also appeared to say that the ink could be put on his 'ass', rather than using the English saying, which is 'arse'.
The tone of his voice also goes up at the end of his sentences, called rising inflection, when he said: 'Does that say Jelly Roll? You put my name on your neck?'
At the end of the video, Harry uses hard r's when he asks: 'Are you serious?'
He later appeared to suggest the tattoo could be put on his 'a**', rather than the English 'a***'.
Anthony Shuster, a communication coach and accent specialist, told the Telegraph: 'You notice that there's a huge difference between the way the King speaks and the way these guys speak.'
It seems Prince Harry is becoming more Californian with phrases he uses and his accent
Speaking of Harry's accent in the clip, he said: 'It's not exactly the stiff upper lip, it's a sort of inert upper lip. There's very little articulation at all.'
Mr Shuster also looked at another video of Prince Harry from 2004, during his gap year where he spent eight weeks in Lesotho.
Harry can be heard saying: 'Yeah it's learning about the culture, isn't it. Different country – not everybody knows about it.'
The language expert said that there is much research about children from affluent backgrounds dropping their t's in order to sound 'less posh'.
But it was in 2019 when the real change shifted after he met Meghan Markle, says Mr Shuster.
When he first introduced baby Archie into the word, Harry said: 'Wow, he's already got a little bit of facial hair as well.' Except his t's became d's, which made the world 'little' sound like 'liddle'.
Mr Shuster told the outlet: 'That's something that's quite distinctly American, is to let your final 't' sort of soften to a 'd'.'
Jennifer Dorman, a linguistics expert, said that his vocabulary has become more Americanised since his big move in 2020.
Language expert Anthony Shuster said it was in 2018 when the real change shifted after he met Meghan Markle
In podcast recordings with his wife in 2021, Harry started peppering his speech with phrases including 'awesome' and 'you guys', she noted.
'It could be that Prince Harry has started to borrow American phrases and words in order to fit in and be understood better by the American press,' she told Cosmopolitan in 2021.
'This could become so habitual that he uses these words when speaking to Brits and Americans alike.
'Or he may just be mimicking his wife: interacting at a close level with someone all the time can cause us to pick up their speaking habits.'
Commenting on his recent tattoo video, one fan said: 'He's picking up American words. That's good.' Another chimed in and said: 'American slang, a bit of the accent, love it!'
But this is not the first time fans have pointed out his change in accent. Last year, Harry had an interview ITV News' Tom Bradby, where he used similar rising inflections and changes in tone.
The Duke of Sussex had developed a habit of ending his sentences with 'right?'
The Duke of Sussex , 40, has previously expressed his joy at living in the States with his children Archie, five and Lilibet, three, describing his life in America as 'amazing'
The two-minute long skit with musician Jelly Roll (not pictured), filmed at New York tattoo parlour East Side Ink, saw people pointing out that he has now gone Cali cool
And the Evening Standard's Royal Editor Robert Jobson noticed that Harry has the 'Meghanism' of ending sentences with 'right'.
He said: 'Now he is using the Meghanism 'right' at the end of sentences. Oh dear. I am amazed Harry believes William will reconcile with him. Why on earth should he?'
And author Ysenda Maxtone Graham also noticed the same thing, tweeting: 'I keep thinking of Harry's constant use of the word 'right?' at the end of his sentences, demanding instant assent, or at least a nod. American-casual, or coercive?'
This comes after a language expert in 2022 that Harry might have picked up a few Americanisms since moving to the States with his wife Meghan and son Archie in 2020.
Former King's College language specialist Tony Thorne says shades of an American accent can be heard in the Duke of Sussex's voice in his most recent interview with US broadcaster NBC.
He says Prince Harry can be heard dropping his 'Ts' in some instances - including when talking about his new home in Santa Barbara, California.
And their son Archie was heard making an adorable comment in his American accent in their £88million Netflix documentary in December 2022.
During his interview with Oprah in 2021, his Americanisms were picked up on again by Judi James, a leading communication and body language expert.
James said being in lockdown with Meghan Markle would have sped up his adoption of Californian English, as she also noted his 'overkill gesticulation' with his hands while speaking.
She told MailOnline at the time: 'Once lockdown ends and he is socialising with other US people I'd expect it to be even more dramatic. 'You can see that through a couple of things, ''I'' comes out as ''Ay'' and when he says ''herself'' he stresses the ''self''.'
'He uses a scooping ritual with his vocal tone, scooping it into a rise at the end, turning statements into questions via vocal tone.
''Together' has a linger on the ''r'' as in ''Togetherr'' and he blends two words together sometimes to create that slight drawl.'
One Twitter user noticed how Harry pronounces security 'securidy'.