Michael Vaughan has claimed Jonathan Trott was celebrating with South African players after they beat England at Edgbaston in 2008.
South African-born Trott was called up into the England squad for this summer's Ashes and made a dream debut with a century at the Oval.
However, former England captain Vaughan has questioned Trott's commitment to his adopted country after witnessing him celebrating with Proteas players.
Trott will be part of the England squad for the upcoming tour of South Africa, but Vaughan says that he was disappointed to see him involved with the opposition in 2008.
In what was his final Test, South Africa won the series by beating England at Edgbaston, and in his new autobiography Vaughan claims he spotted Trott celebrating with the tourists.
"It was a sad day for English cricket that on my last day against South Africa I saw Jonathan Trott celebrating with South Africa, when the week before he had been our 12th man at Headingley," Vaughan wrote in Time to Declare.
"I was going into the press conference and I saw him patting them on the back. It hit home what English cricket has become like."
Although unhappy about Trott being yet another player born abroad but playing for England, Vaughan admitted that his selection was successful.
Vaughan praised the talent of the Warwickshire batsman, who he believes will go on to succeed at the highest level.
"The selection of Jonathan Trott after much fevered speculation proved an excellent decision," Vaughan added.
"He immediately had that look about him of being comfortable at the highest level, and could prove to be a more stubborn version of Kevin Pietersen.
"I suppose you might wish Trott was a bit more English, but after such a brilliant debut it appeared we had found another high-quality batsman."
Trott has responded by rejecting any speculation that he is not fully committed to the England cause, telling the Daily Mail: "My commitment to England is 100 per cent. I've spent seven years working hard to be able to wear the Three Lions and in that time my allegiance has never wavered."
Trott is one of a handful of South Africa-born players in the England Test set-up, after captain Andrew Strauss and Pietersen.