A - Opening Straight

With 40 starters, riders naturally want a good sight of the first fence and after the long build-up their nerves are stretched to breaking point, which means the stewards' pre-race warning to go steady is totally ignored.

It is far easier to be near the lead and settle back into your planned position among the huge group than it is to fight your way up through the no-hopers and there are plenty of those.

Although the first fence is wide enough to accommodate all 40 starters and is quite inviting, it is the pure speed that causes fallers. The year after Aldaniti and Bob Champion triumphed, they and nine others exited at the first fence.

The second looms up very quickly before some riders or horses have properly recovered from the charge to the first and they are still going too fast.

Land safely over the third and a rider can start to relax himself and his mount. Horses feel everything the rider is bodily transmitting from confidence to fear. The communication lines are through the reins to the horse's mouth and on to the brain and via the rider's legs through the ribcage to its heart and onto the brain.

The third has no nickname, yet remains the jockey's bogey fence. With a six-foot open ditch in front of it and standing five feet two inches high, the fence poses several problems including the fact neither horse nor rider may actually see it through sheer weight of numbers bunching towards the middle of the course. The other pitfall is the size and length of leap needed after two lesser jumps.

Precision is the key as standing off a stride too soon leaves a horse vulnerable to being overstretched on landing. Mis-timing the approach can see the horse actually land in the open ditch or clout the fence halfway up. Either way, it is goodbye to any dreams of glory for at least another year.

Fences four and five give everyone time to regroup the senses and get into the rhythm that will conserve vital energy, but there is no time for complacency as the next three fences pose three very different questions.

B - Becher's Brook

The fence is angled at about 15 degrees across the course coming back from the inside rail, which means the horses on the wide outside will rise first but give vital lengths away.

As the course also makes its first turn here, horses are not expecting the ground to disappear under them on landing, so the riders need to let the reins slip through their hands while sitting back in the saddle to enable their body weight to act as ballast to keep the horses hindquarters from overtaking their head!

C - Foinavon

D - Canal Turn

The race can be won or lost here, with a diagonal leap to the inside of the jump taking the fence at a scary angle, but reducing the turn on landing. With 30 or more horses still standing, not every rider has the option of this daring passage.

E - Valentine's Brook to the Melling Road

F - The Chair to the Finish

The 15th fence is The Chair, identical to the nasty third fence but only half its width as the course narrows. This has the effect of assuming higher proportions as yet another trap is waiting. The landing side turf is actually raised six inches above the take-off ground.

This has the opposite effect on horses and riders to the drop at Becher's, as having stretched to get over the open ditch and five foot three inch fence, horses are surprised to find the ground coming up to meet them. This is spectacular when horses get it right and equally so if they miscalculate as it is right in front of the main grandstand.

The 16th is the water jump, which only stands two feet high and acts as a confidence-restorer after The Chair. It also signals to riders the first circuit where survival is paramount has now passed. They can now start to play jockeys and bring tactics into play.

On the second circuit, these two fences are by-passed and Aintree's last obstacle has no fence on it at all.

The 494-yard long run in from the final fence to the finish is the longest in the UK and has an acute elbow halfway to further scrape the empty barrel. Horse and jockey feel every vital breath as if it were molten lava, but with half a sniff of victory, the pain is irrelevant.

Having jumped the last in with a chance, you find reserves that were previously hidden. You are spurred on by the exaggerated sound of rivals shouting to urge tired legs to find more and the horses snorting nostrils flapping noisily with each exhalation.

For numerous riders over the years this elongated run-in has proved mental and physical agony when the winning post seems to be retreating with every weary stride.