Posing the question as to why stars like Guy Martin and Josh Brookes wish to return to the TT has reignited the debate as to why riders seem compelled to race there at all.

After all, the main compulsion to compete in the TT ended when the FIM, in its wisdom, deprived it of world championship status in the 70s, seemingly at the behest of Barry Sheene and Giacomo Agostini.

But there is no shortage of volunteers despite the near-certainty that someone will get killed every year and the average since its inception 110 years ago is twice that. The defence put up by the sports governing body, the ACU, at the time Gilberto Parlotti was killed and Agostini vowed never to race there again was ‘the throttle works both ways’.

But those were the days when many European circuits from Spa to Monza were also highly dangerous and the serious injury ratio per mile raced was not that different from the TT.

Now circuit changes have all but eliminated the likelihood of serious injury from hitting racetrack furniture. The risk now is riders hitting each other as Ian Hutchinson found out when his leg was mangled in a Supersport race at Silverstone - a horror crash which could have ended the career of one of the great roads riders.

The TT is now acknowledged, and accepted, as an extreme sport and comparisons are drawn with other high risk activities. Indeed, largely due to wide television exposure, the audience for this curiosity is now bigger than ever.

Fans from Australia to California whose only racing exposure is Phillip Island or Laguna Seca - or Europeans where Spa and Nurburgring have been largely emasculated - cannot believe their eyes when viewing a John McGuinness on-board video.

And what does the great man himself have to say about the irresistible lure of the Isle of Man. In a Honda video announcing the ‘dream’ team of McGuinness and Martin, he first reminds us all of his not unsuccessful short circuit and World Championship endurance career.

Of the TT, which he first visited with his Dad in 1982 he says: “I just like the whole thing about the TT. I like racing on my own, riding against the clock.The circuit just invites me in. What makes me different on there? Maybe I’ve got a bit more passion for it.

“There are various reasons. It wasn’t for the money, it wasn’t for the glory. It was just racing the track, riding my bikes on the hardest, most difficult track in the world. There’s no greater feeling. You just want more.

“There have been few moments when I’ve thought whether I want to do this any more. I’be seen friends lying in the road. Real good friends. I spent a lot of time with my old friend Mick Lofthouse. He said to me, ‘You’ll be alright at the TT. You’ll be perfect for it’.

“We went and did it and then in practice on the last day he was killed, and I was sharing a room with him in a hotel. That was the hard reality of what can happen on two wheels at the Isle of Man. Joey Dunlop won the race, I was fastest newcomer. I loved it.

“You don’t forget about them. It just goes to the back of your mind and it’s the next race. It happened again when David Jefferies got killed in front of me. And even last year with Paul Shoesmith. That was really, really tough for me. When I saw David on the road it looked like he was asleep. He was laid there, but he was gone. The image of Shoey was dreadful. Tough. Tough.

“But we’ll be off down Bray Hill again, backsides on fire, looking at the next record. Onwards and upwards. I don’t want to fail. But the depth of field is so much stronger, so many more riders. I don’t want to let anybody down but there will be a time when I can’t do the 135/136mph and I’ll have to move over and let the next rider come in. But life will go on and development will continue. But if it does go wrong for me I will have to pay the ultimate.”

Mick Chatterton, now in his seventies and past-President of the TT Riders’ Association, is at the opposite end of the spectrum to McGuinness. Never a TT winner but multi-replica recipient, his passion for the Isle of Man circuit is equal to the great man:

“The mystery to me has always been why some riders don’t do it. I have never been able to understand how anyone who seriously races motorcycles has not got the desire to ride on the TT circuit, and thats the attraction, nothing else just the TT circuit. Anyone who hasn’t done it could never understand the magnetism of the place.

“I personally rode there for 38 years and just lived for it, all other races were just practice for the TT as far as I was concerned. One example of this fanatical relationship with the event occurred in the early 80s. I always had sleepless nights when it got close to the time when the entry confirmations were due to arrive not knowing if I would be accepted or not.

“This particular year I nervously opened the envelope from the ACU as usual to find I had been refused an entry. This hit me like a bombshell, not doing the TT was completely unthinkable and unacceptable to me. I couldn’t go into work that day as I couldn’t think about anything else. Instead I spent a fortune on phone calls to the ACU, with no success, so decided to make the 200-mile trip to central London, where the ACU headquarters were at the time, to speak to them face to face.

“I still remember the look of dismay on the face of Derek Jackson the secretary at the time when I went into his office and he stuck to his decision for two or three hours and several cups of coffee before relenting and giving me two reserve rides, probably to get rid of me.

“The feeling of relief was tremendous and I couldn’t feel happier on the long drive home not caring if I still had a job to go to or not. I was going to the TT that was all that mattered. This passion for the race still exists and it is no surprise to me to see riders there year after year or returning after a short absence. The pull of the place is just too strong to resist.”