Calls for the number of runners in the Grand National to be reduced in the aftermath of Saturday’s big race at Aintree have been given a firm thumbs down by Nicky Henderson.

The master of Seven Barrows, who has yet to break his duck in the big race, thought for a brief moment that long-time leader Mister Coffey was going to win the first chase of his career when three lengths clear at the penultimate fence, only to tire and finish eighth under Nico de Boinville.

"There was a moment," laughed  Nicky Henderson."The only thing you could say, is if people are going to protest about what horses do, have you ever, ever, ever seen a horse not enjoy himself more?

"He absolutely loved it, didn't he? It is absolutely living proof that this is what these horses want to do.

"There is the odd one that gets a bit sulky at times, but watching most of these horses, that can only tell you one thing – they love their job."

The start of the four-and-a-quarter-mile handicap was delayed by almost 15 minutes as animal rights protestors got on to the Liverpool course and attempted to secure themselves to railings and fences.

The delay meant that horses, who were already saddled and in the parade ring, were removed for a time, returning to the saddling boxes and pre-parade ring.

When the race was eventually given the go-ahead, Hill Sixteen, who had never before fallen, suffered a fatal injury at the first fence and five others were unseated. Two more fell at the second fence, although none fell thereafter.

Henderson scoffed at suggestions that the field size – 39 horses lined up from a maximum of 40 runners – is too big and hinted that the delay caused by protestors may have affected some horses more than others.

He said: "It doesn't do them any good, but to be fair, everybody did their best and did as good a job as they could to get the race going.

"They did well to get wind of what was going to happen and what they (protestors) were planning. I think we all expected it to happen. They were going to have a go, but it was a pretty pathetic show.

"There are certain horses that it would affect. With Mister Coffey, it didn't worry him.

"I just let his girths out after they went back to the top paddock. That is a reasonable thing to do, because once you tighten their girths, they know what they are doing.

"He was very good, but if it had been Jonbon, it would have been a shambles. It would have been game over. He couldn't have taken that (delay).

"But as to suggestions we need to reduce the field size, no. We should have had a reserve.

"It is part of the spectacle. That is what the race is all about. The start is always going to be difficult with 40 horses – everyone wants to be up there, of course they do.

"But it's the essence of the race. We are not fiddling around with some little gymkhana, you know.

"The race wasn't helped by the protestors and it depends on your horse, but Mister Coffey is not someone who is going to get himself in a fuss.

"Had it been Jonbon, it would have been a different ball game."

Eight-year-old Mister Coffey will be campaigned with the National in mind next season, following his excellent showing.

Though he has yet to win in nine starts over fences, he has been running in very good company. Runner-up in last year's Kim Muir at Cheltenham, he has twice finished as bridesmaid in two decent handicaps this season before finishing placed in the National Hunt Chase on returning to the Festival meeting last month.

Henderson added: "Of course we are going to build around the National next year.

"Mind you, I'm going to try to win a race with him first.

"He has been a bit unlucky, but it is not as if we have gone down to the bottom level to try to win a maiden chase.

"He's been to the Cheltenhams and Aintrees and I would have thought we'd go to the same route to the end, but maybe the sensible thing to do is to try to win a couple of little races before Christmas then put him by for Cheltenham and then the National. He is improving."

Though Jonbon gave Henderson and jockey Aidan Coleman an easy success in the Magull Novices' Chase to open Saturday's card, the trainer was still scratching his head after Marie's Rock was overhauled by Sire Du Berlais in the Liverpool Hurdle.

The Stayers' Hurdle winner looked well held turning for home, but came with a remarkable rattle to outstay his rivals, with Marie's Rock having looked all over the winner under De Boinville when leading on the bridle jumping the penultimate flight.

Henderson, who also saddled eventual fifth Champ, added: "No one saw that winner coming. I knew where the winner was because he was in the JP (McManus) colours upsides Champ at the back the whole time.

"I was always looking back to see where Champ was and the winner was going worse than Champ. Quite a lot worse!

"You couldn't believe it. When we arrived on the bridle two out, you could not believe that was going to happen.

"She's fine this morning. She will go three miles all year now."