Bookmakers believe punters will go angling for Seabass to put Katie Walsh into the record books as the first female jockey to win the Grand National.

The combination filled third place 12 months ago and the bookies think there could be a public plunge on the Irish rider as she teams up once again with Seabass, trained by her father, Ted.

She is likely to carry plenty of an estimated STG200 million ($A294 million) wagered on the Aintree spectacular, which will be watched by a worldwide television audience of an estimated 600 million on Saturday (Sunday 0115 AEDT).

The Walsh family could well hold the key to where the bulk of the money goes as the trainer also saddles Colbert Station, the mount of Tony McCoy, while his son Ruby is aboard the well-fancied On His Own for Willie Mullins.

"With half the UK adult population expected to have a flutter, we anticipate more than STG200 million will be wagered on the world's most famous race," Betfred's Andrew Griffiths said.

"Katie Walsh is aboard Seabass again who was backed off the boards last year. If her supporters come out in force, there is every chance she could be aboard the National favourite come the off."

Coral go 15-8 that a member of the Walsh family wins the race.

Victory for Seabass would also cost Ladbrokes plenty, but they can sense a second triumph in the race for McCoy.

"A win for Katie Walsh would be the fairytale story and could cost us a small fortune," a spokesman said.

"But the shadow of Tony McCoy and Colbert Station looms large in the betting and we suspect it could be the champion jockey who spoils Katie's party.

"Females will go into a fluttering frenzy for Katie and Seabass but Tony McCoy is still the pied piper of the punters. They dance to his tune on the biggest day of them all."