Grand National 2016: Aintree field headed by Many Clouds

Many Clouds beat Saint Are in a close finish in last year's running

Last year's winner Many Clouds heads Saturday's Grand National field after the 40-runner line-up was confirmed.

The 2014 winner Pineau De Re was among those to miss the cut for the famous Aintree race.

Lower-rated horses are balloted out, with The Romford Pele occupying the number 40 slot.

There were no withdrawals in Thursday's final declaration stage. Four reserves are on standby should any runner pull out before 13:00 BST on Friday.

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Pinstickers' guide

What are the prospects for this year?

Many Clouds is 7-1 favourite ahead of 10-1 chance The Last Samuri and 12-1 shot Silviniaco Conti.

Coverage of the race, over 30 fences and nearly four-and-a-half miles, is expected to be followed by 600 million people worldwide.

Organisers have put back the time of the race by an hour to 17:15 BST in an effort to further increase the audience.

Why have some leading contenders missed out?

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

Some trainers are faced with the tricky task of trying to ensure their contenders perform well enough to get a rating which guarantees a run, without landing a big weight that hampers their chances.

Pineau De Re is now in the twilight of his career, at the age of 13, and his rating has dropped.

No horse of that age has won the National since Sergeant Murphy in 1923.

The British Horseracing Authority has indicated it is open to reviewing the entry system ahead of next year's National.

History in the making?

Top weight Many Clouds will seek to become the first horse since the legendary triple victor Red Rum in the 1970s to win back-to-back runnings.

Victory would see jockey Leighton Aspell, who also triumphed aboard Pineau De Re two years ago, become the first rider to win three years running.

Officials believe modifications to the fences, and other alterations, introduced three years ago have helped improve safety.

Since the changes, there have been no fatal injuries in the National itself, although two horses died in other races at the three-day meeting last year.

Jockey Leighton Aspell - seen here after his 2014 triumph - is aiming for an unprecedented three wins in a row

Aspell and Many Clouds finish clear of the rest to win the 2015 race

The National course was rated as Soft, Good to Soft in places on Thursday morning

Security around the meeting - which was postponed in 1997 after a bomb scare - is tight