The alleged incident is believed to have taken place near the start of England’s tour, while Bancroft was playing for Western Australia, and before he was called up for his Test debut this week. Sources suggest it was more of a coming together than a violent assault, and the police were not called.

A representative of the England and Wales Cricket Board met with Bairstow after the close of the fourth day’s play in Brisbane to hear his version of events, and afterwards the body released the following statement: “At close of play in Brisbane, we were made aware of allegations of an incident in Perth three weeks ago.

Ashes First Test - in pictures Show all 33 1 /33 Ashes First Test - in pictures Ashes First Test - in pictures Day 1 Mitchell Starc celebrates dismissing Alastair Cook early on day one. Getty Ashes First Test - in pictures Day 1 Alastair Cook made just two runs before being caught in the slips. Getty Ashes First Test - in pictures Day 1 Mark Stoneman (left) and James Vince (right) fought back for England to steady the ship. Getty Ashes First Test - in pictures Day 1 Nathan Lyon (not pictured) runs out James Vince for 83. Getty Ashes First Test - in pictures Day 1 Australia celebrate after Nathan Lyon's dismissal of James Vince. Getty Ashes First Test - in pictures Day 1 James Vince leaves the Gabba pitch to applause after being run out for a hard-fought 83 on day one. Getty Ashes First Test - in pictures Day 1 Pat Cummins took the wickets of Mark Stoneman and Joe Root either side of tea Getty Ashes First Test - in pictures Day 1 Moeen Ali slogs Nathan Lyon for six Getty Ashes First Test - in pictures Day 2 Mitchell Starc starts the day with a ferocious spell Getty Ashes First Test - in pictures Day 2 James Anderson removes Peter Handscomb early as Australia's reply stuttered Getty Ashes First Test - in pictures Day 2 Jake Ball took the crucial wicket of David Warner Getty Ashes First Test - in pictures Day 2 But Australia battled back into proceedings on the shoulders of their captain Getty Ashes First Test - in pictures Day 2 Steve Smith passed fifty as Australia dug in and clawed their way back Getty Ashes First Test - in pictures Day 3 Stuart Broad claimed a brilliant catch and bowled to dismiss Mitchell Starc Getty Ashes First Test - in pictures Day 3 England have a big fitness concern over James Anderson Getty Ashes First Test - in pictures Day 3 Steve Smith's battling innings gave Australia the advantage on day three Getty Ashes First Test - in pictures Day 3 Steve Smith celebrates reaching his century Getty Ashes First Test - in pictures Day 3 Steve Smith's 141 not-out has given Australia the advantage in the first Test of the Ashes series Getty Ashes First Test - in pictures Day 3 Stev Smith leaves the field after his magnificent 141 not-out gave Australia a lead of 26 runs Getty Ashes First Test - in pictures Day 3 Australia made the most of a quickening Gabba pitch Getty Ashes First Test - in pictures Day 3 Josh Hazlewood celebrates the dismissal of Alastair Cook Getty Ashes First Test - in pictures Day 3 Joe Root is hit on the helmet by a Mitchell Starc bouncer Getty Ashes First Test - in pictures Day 4 Nathan Lyon celebrates after having Mark Stoneman caught Getty Ashes First Test - in pictures Day 4 Joe Root celebrates passing his half-century in the second innings Getty Ashes First Test - in pictures Day 4 Josh Hazlewood successfully appeals for LBW against Joe Root Getty Ashes First Test - in pictures Day 4 Joe Root trudges off the Gabba pitch after being dismissed LBW by Josh Hazlewood Getty Ashes First Test - in pictures Day 4 Moeen Ali is stumped by Tim Paine off Nathan Lyon's bowling Getty Ashes First Test - in pictures Day 4 Mitchell Starc celebrates taking the wicket of Jonny Bairstow Getty Ashes First Test - in pictures Day 4 Jonny Bairstow leaves the field after being dismissed by Mitchell Starc Getty Ashes First Test - in pictures Day 4 David Warner salutes his teammates after passing 50 in the second innings Getty Ashes First Test - in pictures Day 4 Cameron Bancroft scored his maiden Test 50 as he shared a partnership of 114 with David Warner Getty Ashes First Test - in pictures Day 5 Cameron Bancroft and David Warner celebrate hitting Australia to victory Getty Ashes First Test - in pictures Day 5 David Warner and Cameron Bancroft hit the 56 runs required on Monday morning to seal First Test victory Getty

“There has been no report of any incident from the venue, security or police, and there was no injury reported. Following an initial conversation with Jonny Bairstow tonight, we understand the context and will follow up with England players and management after the Brisbane Test.”

Central to the ECB’s investigation will be to establish whether this is a cause for genuine alarm – particularly in the wake of Ben Stokes’ arrest in Bristol in September – or a mischievous attempt to derail England’s Ashes challenge ahead of next week’s crucial Adelaide Test. Certainly the timing of the revelation is curious, as is the manner in which it emerged in the Australian media just as England were tumbling to defeat.

Bairstow was repeatedly targeted with sledging from the Australians on Sunday (Getty)

Some Australian players, including Bancroft’s opening partner David Warner, were believed to be referring to the incident in the middle while Bairstow was batting. Yet Bancroft’s management were unaware of the incident until it emerged on Sunday, and so too were many within the Australian setup.

Whatever the truth of the situation, it is an unwelcome distraction for England, putting captain Joe Root even further on the defensive as he plots a way back into the series. Australia are unlikely to encounter many difficulties in knocking off the 56 runs required for victory on day five, and given that no England side has come from behind to win an Ashes series in Australia since 1954-55, Root’s task was already formidable enough.

The wider issue, of course, is whether the England team has a flaw in its culture that leaves itself vulnerable to alcohol-related mischief. Following the Stokes incident, the squad drew up its own code of conduct for the tour, central to which was an agreement not to go out drinking in the days leading up to a game.

Bairstow was on the same night out as Stokes in Bristol (Getty)