If the 155 previous editions of the world's most famous race have taught us anything, it is the Grand National's capacity for surprise. Today the usual maximum field of 40 will stare down towards the first line of bright green fences and know that Bechers Brook lies in wait just six obstacles away. It's a pretty grim piece of certitude but the best available.

The nature of racing's most gruelling test is that if the world's most famous fence doesn't strike, there are 29 others with their own way of bringing you down.

No one knows that better than Paul Nicholls, who has been dealing with the pressure of training the ante-post favourite, Ad Hoc, ever since he was cruelly brought down four fences out last year.

Remarkably, Nicholls also has four other fancied runners and his main jockey, Ruby Walsh, a winner on Papillon in 2000, has added to the mix of uncertainty by preferring the claims of Shotgun Willy.

The Somerset trainer volleyed some criticism at the watering policy on the Mildmay course yesterday but the ground on the National course appeared genuinely "good" in the Topham Trophy.

The Nicholls team alone outguns the Irish challenge numerically but only one horse can be in the winner's enclosure and coincidence backers look set to pile into Youlneverwalkalone.

One bookies spokesman has exuberantly described the horse, ironically owned by Manchester United's most famous shareholder, JP McManus, as "the best-backed horse in National history" and outlined a scenario where every Liverpool and Celtic fan in the world would pile into the horse.

Since the National has a 500 million TV audience worldwide, that could be quite a pile and the power of popular money on an Irish fancy was proved by those titanic gambles on Bobbyjo (1999) and Papillon (2000).

The other main Irish contender is Monty's Pass and a fairytale story of how his Co Cork-based trainer, Jimmy Mangan, a small operator, trained the National winner would have the colour writers licking their lips.

The National seems to demand such stories. The fences might have been modified since the days of Red Rum but in between the capacity of the old place to continually make millions gasp has been proven time and again.

Part of that is the possibility of a long-priced shock and in the last 10 years alone there have been 20 to 1, 33 to 1 and even 40 to 1 winners. It's less than 20 years since Last Suspect was a 50 to 1 shocker.

He was a "character" transformed by the special demands of Aintree and those looking for a similar result today could do worse than looking at the longest-priced of the Irish runners.

Cregg House was a 100 to 1 shot with many firms yesterday which is a bit of an insult to a horse talented enough to be twice placed at the Cheltenham Festival. Built into the price, however, is the "character" factor that caused Cregg House to refuse in the Irish National last year. He is a type that could do that again or take to the atmosphere like a duck to water. If it's the latter, Cregg House, trained by 84-year-old Paddy Mullins, has the ability to go well for a long way.

Winning it, however, is a different matter. Stamina could be a problem to Monty's Pass, a hard race in the Gold Cup might do for Chives while Ad Hoc's chance might have gone last year.

Jockey Barry Geraghty's decision to pass up the chance to ride Youlneverwalkalone is not confidence-inspiring, while Tony McCoy's presence on Irish Bleu may make that one an unrealistic price.

Shotgun Willy looks to have a solid chance, especially now that the watering policy seems to have supposedly produced ground more dead than alive.

In contrast Gingembre (French for ginger) is proven on every type of surface, already has a Scottish National under his belt and has the class to have had the Gold Cup as a realistic option earlier in the year. It's a pretty convincing mix and there is also the story factor.

Trainer Lavinia Taylor, and her husband, John, used to be pig farmers in the Australian outback before returning to train in the UK at a yard from which two previous National winners emerged.

That's a National profile, but then you never know here.