I have a 2012 Portfolio S and have just had the same problem, looks like a seam has split. I was in the middle of Wales at the time. Cost £240 for the part from jag dealer but they unable to fit for about a week. Asked small local garage and they did the job within a couple of days and only charge £140 to fit, approx 4 hours work. Have recently had a problem with the passenger side window, cable snapped, looks like it had rusted through, another £140 for part plus fitting.