Why the Grand National is the 'Wimbledon' of hunt racing

    Ditcheat, Somerset, England (CNN)Imagine galloping 4.3 miles in a group of 40 horses, jumping 30 fences the size of small cars.

    Welcome to the Grand National, the most grueling and spectacular steeplechase in the world.
    The 172nd edition of the race, staged on April 6 at Aintree Racecourse in Liverpool, England, offers a record prize money pot of £1 million ($1.3 million). The three-day Grand National festival will be watched by 150,000 spectators on the course and a global television audience of over 600 million.
      The most valuable jump race in Europe "is a bit like Wimbledon," Clifford Baker, head lad at Manor Farm Stables, the highly successful yard of trainer Paul Nicholls in Ditcheat, England, told CNN Sport.
      "It's fantastic, there are so many countries watching it, and it is such a special race," said Baker of the ultimate test for both rider and horse. "It is the most famous race in the calendar, and the hardest to win."
      Becher's Brook is one of the toughest jumps at Aintree racecourse.

      Red Rum

      Nine-year-old Tiger Roll, owned by Ryanair boss Michael O'Leary, is a short-priced favorite at 7-2 to successfully retain his Grand National crown after he won the Cross Country Chase last month in Cheltenham by 22 lengths.
      Still, being the favorite does not guarantee success in a long race with so many tricky obstacles and horses taking part. The last time the outright favorite won the National was in 2005 when Hedgehunter triumphed.
      The last horse to win back-to-back Grand Nationals was the legendary Red Rum in 1973 and 1974. The bay gelding, trained by Ginger McCain, finished in second place in 1975 and 1976 and won for a record third time in 1977.

      Becher's Brook

      Nicholls is a 10-time National Hunt champion trainer, with more than 3,000 victories, but his lone Grand National victory came in 2012, when French-bred Neptune Collonges, a 33-1 shot ridden by Daryl Jacob, won in a photo finish after a dramatic race that saw two horses suffering fatal injuries.
      "It's a completely unique race," Nicholls told CNN Sport at his stables in Ditcheat, England. "Actually, funnily enough, we won it with the best horse we've ever run in the race. A lot of horses don't like it, a lot of things happen."
      Take Becher's Brook for example. It's one of the Grand National's most notorious obstacles which was named after Captain Martin Becher, who landed into the brook during the first edition of the race in 1839.
      Clifford Baker at Manor Farm Stables.
      The sixth fence on the first lap and the 22nd fence on the second lap, Becher's Brook is 1.47 meters on take-off, but drops to 1.73 meters on the landing side. It is this drop that has made it one of the most treacherous fences in hunt racing.
      In 2004, nine horses failed to clear Becher's Brook as they either fell, refused or were brought down in the first lap. A year later, 20-time champion jockey Tony McCoy and Clan Royal were leading the race by six lengths when they were taken out by two loose horses at Becher's Brook during the second lap. McCoy, who was thrown out of the saddle, eventually won the race five years later with Don't Push It.
      Another daunting obstacle is The Chair, the biggest jump of the entire race which serves as fence No. 15. Located in front of the grandstand, it is 1.58 meters high, and features a wide open ditch. Luckily for riders and horses, it only has to be jumped once.
      Neptune Collonges on the way to victory in the 2012 Grand National.

      'Unique test'

      Addressing safety and animal welfare concerns, Grand National organizers decided to reduce the drop at Becher's Brook to between 10 inches on the inside and six inches on the outside after the 2011 race.
      Two years later, plastic frames were introduced in some obstacles, while the start was brought forward by around 90 yards in order to bring the horses closer to the first jump.
        "They are just big fences, but they are nothing like they used to be," said Nicholls, who may saddle 66-1 shot Warriors Tale for the Grand National depending on the ground at Aintree, where rain is expected this week.
        "They've done so much work on the fences these days," he said. "They are smaller and they are more inviting. Actually, people have got this thing about the fences, 'Ooh they are big.' But you walk round and you think 'Actually, they are not that big.' It's just that you have got 40 horses, it's a unique test."