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A view of the Aintree course on which the Grand National will be run

Randox Health Grand National Dates: 6-8 April Venue: Aintree Grand National: Saturday 8 April, 17:15 BST Coverage: Commentary on BBC Radio 5 live & BBC Radio 5 live sports extra, live text coverage of the Grand National on 8 April on the BBC Sport website and app ( full coverage details )

Last year's runner-up The Last Samuri heads the line-up after a final field of 40 runners was named for the Grand National at Aintree on Saturday.

Pendra was the only withdrawal on Thursday, leaving Doctor Harper as the last horse to make the cut.

Vieux Lion Rouge and Definitly Red are the bookmakers' favourites, at about 10-1, for the famous race.

Four reserves are on standby should any runner pull out before 13:00 BST on Friday.

They are Bless The Wings, Knock House, Sambremont and Viva Steve.

Coverage of the National, over 30 fences and more than four and a quarter miles, is said to be followed by 600 million people worldwide.

The race is again due to start at 17:15 BST, having been put back an hour by organisers last year in in an effort to further increase the audience.

Latest odds 10-1 Vieux Lion Rouge, Definitly Red 14-1 Cause Of Causes, More Of That, Blaklion, One For Arthur 16-1 Pleasant Company, The Last Samuri 20-1 Ucello Conti, Saphir Du Rheu, The Young Master 25-1 Bar (Approximate prices as of 10:00 BST, Thursday 6 April)

The National is a handicap chase, with each runner allotted a different weight to carry by the official handicapper Phil Smith.

With 11st 10lb, The Last Samuri will bid to become the first top-weight to triumph since the legendary Red Rum in 1974.

After Pendra's withdrawal, leading owner JP McManus has three runners, with retained rider Barry Geraghty confirmed to ride More Of That, trained by Jonjo O'Neill.

Amateur jockey Jamie Codd is on Cause Of Causes, from the Gordon Elliott yard, and the Anthony Honeyball-trained Regal Encore will be partnered by Robbie Power, winner of last month's Cheltenham Gold Cup with Sizing John.

Doctor Harper's inclusion means trainer David Pipe has the most contenders - four - with Ballynagour and La Vaticane joining leading fancy Vieux Lion Rouge.

Terminally ill five-year-old boy Bradley Lowery is to be given honorary 41st place in the National racecard.

Armed police will be in attendance at the course as the three-day meeting gets under way on Thursday.

This year's race comes in the wake of the Westminster terror attack and marks the 20th anniversary of the National being delayed by an IRA bomb scare.

Merseyside Police Commander, Chief Superintendent Claire Richards, said: "Racegoers can expect to see high visibility policing across the three days of the event.

"They may also see an armed presence but I want to reassure them that this is not in response to any direct threat aimed at the festival but just as a visible reassurance for the thousands of people who will come through the gates over the three days."

Aintree first day highlights - Thursday

Can Cue Card win again at Aintree after Cheltenham fall?

Colin Tizzard's popular chaser Cue Card, who fell at the third-last fence for the second successive year in the Cheltenham Gold Cup in March, will bid to win the Betway Bowl again after succeeding 12 months ago.

The Paul Nicholls-trained Silviniaco Conti, winner in 2014 and 2015, is among his rivals.

Champion hurdler Buveur D'Air leads runners in the Aintree Hurdle (15:25), alongside stablemate and Cheltenham runner-up My Tent Or Yours and 2014 winner The New One.

On The Fringe and Pacha Du Polder head contenders for the Foxhunters' Chase over the Grand National fences (16:05) .

Enda Bolger's On The Fringe has won the last two renewals, but could only finish fourth behind the Nicholls-trained Pacha Du Polder at Cheltenham.