Winston threw five interceptions and lost a fumble as the Bucs were soundly beaten by their NFC South rivals.
Tampa Bay games are very often decided by which Winston turns up. We see the best and the worst of the Buccaneers quarterback on a seemingly week-to-week basis.
And an interception on the first play of the game suggested it would be the bad Winston who had arrived in England's capital.
He tried to fit the ball into Mike Evans but instead found Panthers cornerback James Bradberry.
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Carolina, considered the away team for today's game, took over in good field position and kicker Joey Slye ended up scoring a 49-yard field goal.
There are reports that Panthers quarterback Kyle Allen could keep the starting job over Cam Newton when the 2015 NFL MVP returns from a foot injury that has kept him out since Week 2.
And Allen showed just why that may be the case with a stellar 12-play, 99-yard drive that culminated in Christian McCaffrey's first touchdown of the day.
Allen completed passes of 21 and 23 yards to put Carolina in scoring position before McCaffrey converted from one yard out on 4th & goal.
The momentum was with the Panthers, up 10-0, and it needed a big play from the Bucs to get back into the game.
And they got one.
Cornerback Ryan Smith, active for just the second week after serving a four-game suspension, forced a fumble from Panthers’ punt returner Ray-Ray McCloud and the ball was recovered by linebacker Kevin Minter.
Winston returned to the field and, after finding tight end O.J. Howard for a 30-yard gain, watched as Ronald Jones punched the ball in from five yards out for the Bucs' first touchdown of the day.
Tampa Bay's joy was short-lived, though.
Winston's attempted pass to Bobo Wilson was tipped by Bruce Irvin and Javien Elliott came up with the interception.
Two quarters, two interceptions. Oh, Jameis.
McCaffrey then made Winston pay with a weaving 25-yard touchdown, leaving Bucs defenders in his wake as he found the end zone for the second time of the day.
The Panthers led 17-7 and Winston wasn't done with the turnovers.
Tampa Bay were in position to reduce the deficit but Vernon Butler forced Winston to fumble the ball and it was recovered by Irvin.
A quick three-and-out gave Bruce Arians' side one more opportunity to score before half-time and they came agonisingly close to a well-needed touchdown.
Mike Evans got clear of Bradberry but couldn't hang on to Winston's deep ball, leaving a possible seven points on the field.
The Panthers extended their lead to 20-7 through another Slye field goal and things got even better for them in the game's next drive.
Carolina's defense had Winston figured out and Luke Kuechly benefited from the former first-overall pick's errant ways with an interception.
It was Winston's third pick of the day and Panthers WR Curtis Samuel capitalised on the turnover with an eight-yard touchdown run to make it 26-10, with Slye converting the extra point attempt.
How much longer will Winston be the starting quarterback in Tampa? Buccaneers head coach Arians is known as a quarterback whisperer but it's not working out with the former Florida State QB right now.
And Arians and Winston had to sit and watch as Carolina pieced together a 10-play drive that ended with Samuel scoring another touchdown.
Tampa Bay's trip to Europe wasn't working out as planned.
They made it a two-score game, however, when Winston found tight end Cameron Brate in the endzone and then converted the two-point attempt.
The Bucs had more than 12 minutes in which to recover their 34-18 deficit and they got the ball back when the defense forced a three-and-out.
But Winston couldn't move the chains and were forced to punt it back.
It won't just be Winston who will be called into Arians' office tomorrow morning. A muffed punt by Bobo Wilson allowed the Panthers to take over on Tampa's 17-yard line.
It led to a 29-yard field goal by Slye and an unassailable 37-18 lead for the Panthers.
Bucs RB Dare Ogunbowale scored a touchdown and Winston converted the two-point attempt to make the scoreline look more respectable.
But there was still time for two more Winston interceptions.
His fourth of the game was to Ross Cockrell and his fifth to Bradberry, compounding a miserable performance for the Bucs quarterback.
A convincing 37-26 win for the Panthers, then. For Tampa Bay, the inquest begins now.News Now - Sport News