The Grand National, run at Aintree near Liverpool since 1839, is a handicap steeplechase run over a 4 mile, 856 yard distance, with thirty challenging fences to jump along the way.

One of the premiere events in British and world horse racing, it is watched by over 500 million people worldwide, and is popular even among those who don't normally watch or bet on horse racing.

The course has a reputation as one of the ultimate tests of both horse and jockey, with most failing to complete the required two circuits - in 1928, only two did so, while the most to finish is 23, in 1984.

The course record was set in 1990, with Mr Frisk finishing in a time of 8 minutes, 47.8 seconds.

The largest field was that of 66 runners in 1929, though this is a record that certainly won't be broken by tomorrow's 166th race - the field is capped at 40.

Many horses and jockeys take on the race multiple times during their careers - jockey Tom Olliver ran 19 times between 1839 and 1859, while horse Manifesto (foaled 1888) ran a record eight times (1895-1904), with wins in 1897 and 1899.

More recently though, the most wins by a horse is Red Rum (foaled 1965), winning a record three times, in 1973, 1974, and 1977, while finishing in second place in 1975 and 1976.

The most wins by a jockey is five, by George Stevens who rode Freetrader (1856), Emblem (1863), Emblematic (1864), and The Colonel (1869, 1870).

The race is not often won by the favourite, and on five occasions has been won by a 100/1 outsider (starting price). The horses sharing the record for longest odds winner are Tipperary Tim (1928), Gregalach (1929), Caughoo (1947), Foinavon (1967) and Mon Mome (pictured, 2009).

Long shots who could join them with a win in tomorrow's race include Major Malarkey and Mumbles Head, both currently 100/1 outsiders.

Pentiffic and Mortimers Cross are waiting in reserve at 100/1 and 150/1, respectively.

Neither a favourite nor a rank outsider, 33/1 Neptune Collonges won last year, beating second-place Sunnyhillboy by a nose in the closest ever finish - only the third grey to win the race.

The first female jockey to ride in the Grand National was Charlotte Brew on Barony Fort, in 1977 - although she did not finish the race, with the horse refusing at the 26th fence.

Geraldine Rees became the first to complete the course in 1982.

Katie Walsh was the first female jockey to earn a placed finish in last year's race - while she led over the final fence, she ended up finishing third on Seabass.

This horse/jockey pairing will return in tomorrow's race, so will Katie, still an amateur, become the first female jockey to win? Short odds of 9/1 indicate this is a real possibility.

Katie's brother, Ruby, will also ride in the race, on the favourite, 15/2 On His Own - with a little luck for both Katie and Ruby, it could be a very good day indeed for the Walsh family!