Grand National Betting Taking Shape Betting on this year's Randox Health Grand National is expected to be close to record levels, with upwards of 150 million pounds being wagered on the Aintree race. The National remains by far the UK's largest horse racing event. Among the early favourites with punters has been One for Arthur, despite a current handicap of 137. Foaled in Ireland but trained by Lucinda Russell in Scotland, the eight-year-old gelding is widely available at 20/1. The horse will have no fear of Aintree's fences after his fifth place in December's Becher Chase, and has notched up wins at Kelso and in the Warwick Classic Chase this season. Russell called his Becher peformance "fantastic" and said that he would be given a quiet run-up to the Grand National, not racing again until his return to Aintree. The Last Samuri disputing the lead with Vic Canvas in 2016 Grand National©Healy Racing PhotosThere is also Irish interest in the shape of last year's National runner-up The Last Samuri, who is also being heavily backed. The chestnut gelding began his career in Irish Point-to-Points, winning his maiden at Taylorstown before joining Kim Bailey. He was among the also-rans on his seasonal debut in the JNWine Champion Chase behind Valseur Lido but again showed his liking for the National fences when third in the Becher Chase in December. At nine years old, The Last Samuri is entering the absolute prime of his racing career, and it's no surprise that he is currently the favourite with many bookies at around 16/1. Another well fancied likely runner is the Gordon Elliott trained Don Poli, who has been backed in to 20/1 in recent weeks. He impressed in winning the Lexus Chase at Leopardstown over Christmas and has two other Grade One victories to his name. He again ran with distinction when third in Sunday's Irish Gold Cup and his trainer is intending to run him in the Cheltenham showpiece next month before a crack at Aintree. The eight-year-old gelding's stamina and appetite for a scrap should serve him well in the National, although he may have problems if Aintree serves up one of its customary fast early breaks. French-born challenger Vieux Lion Rouge has to be taken seriously after winning the Becher, and made light of his 66/1 starting price at last year's Grand National to come home a highly creditable seventh despite being only seven years old at the time. Trainer David Pipe does not want to over-race him, planning on only a single outing before the big one. He admits to concerns that Vieux Lion Rouge may be "borderline" to make the field, despite his 146 rating. Punters rate him at 25/1, but hard ground could scupper his chances. Shutthefrontdoor(center) - before winning the Irish Grand National 2014©Healy Racing PhotosA notable name further down the betting is Shutthefrontdoor, the beaten favourite under AP McCoy in 2015 and Irish Grand National winner in 2014. Now aged ten, Shutthefrontdoor may not have many more chances at the sharp end of the field, but 50/1 may still represent value. Trainer Jonjo O'Neill will be hoping to find good ground at Aintree, feeling that the horse can be awkward to control and tire more easily in heavy conditions. With many people in the UK placing their only bet of the year on the Grand National, even the most unlikely outsiders going to post at three-figure starting prices often attract significant betting interest, skewing the odds in a way almost unique to this race. The prize fund for the Grand National Festival has been increased to top three million pounds for the first time, with the National itself now featuring a fund of almost one million pounds. The Randox Health Grand National takes place at Aintree on Saturday, April 8, with the field going to post at 5:15pm UK time.