Lewis Hamilton's subdued demeanour at last weekend's Korean Grand Prix not only raised a few eyebrows, but also led to growing concern over the British driver's state of mind.

While 2011 has not been the best of seasons for the 2008 F1 world champion, his mood could not simply be explained by the rigours of F1, and his lack of excitement at breaking Red Bull Racing's 15-race run of pole positions was genuinely surprising. While experts were suggesting that the McLaren man needed a long break from the sport - which would undoubtedly help - other sources believe that there may be more fundamental reasons for his malaise.

The British tabloid press, the Daily Mirror among them, have speculated that things may not be entirely happy back at the ranch, with Hamilton and popstar partner Nicole Scherzinger having spent long periods apart as their respective schedules take them away from home. While the Briton has now had three Asian races in a four-week period, Scherzinger has taken on the role of judge and mentor on the US version of X Factor which. combined with her own solo singing career, has led to a long separation.

"Nicole and Lewis are both extremely busy people who lead incredibly hectic lives," a source told the Mirror, "Of late, their schedules have proven pretty unworkable and they have not been able to see as much of one another as they would have liked. They still speak on the 'phone, but this isn't the same as face-to-face contact and things have been rough for the past six weeks."

The source offered some further words of hope, but still admitted that only time would tell as to whether the relationship would last.

"Both want it to work, but it's fair to say things are rocky," it was revealed, "But they have rowed before and worked things out. As far as both are concerned, there is still hope."

As well as the enforced separation, however, come suggestions that pressure to commit and start a family may be behind Hamilton's demeanour, particularly after Scherzinger's father claimed that the Briton had proposed to his daughter. However, Scherzinger is seven years Hamilton's senior, and perhaps their respective biological clocks are no longer in synch....