McCain, whose success at Aintree made him synonymous with the race, passed away just two days short of his 81st birthday following a battle with cancer.
A taxi driver from Southport, McCain forged his own path in racing and found fame with Red Rum, whom he saddled to a hat-trick of National triumphs during the 1970s.
McCain became only the second trainer to win the famous steeplechase four times when Amberleigh House triumphed in 2004.
His son, a jockey-turned-trainer, continued the family tradition earlier this year when he saddled National winner Ballabriggs.
“What he achieved with Red Rum was amazing,” said champion jockey Tony McCoy. “I know how difficult it is to win one Grand National and it looks impossible to win two.”
Amberleigh House owner John Halewood added: “I remember him not just for the horses we had together, but also for the great fun we shared. It is a very sad end of an era. He is a true legend.”
Jenny Pitman, the first woman to train a National winner with Corbiere in 1983, called McCain “irreplaceable”. “Ginger’s words when Red Rum died come to mind – ‘We’ll miss the old bugger’,” she added.
Former racing commentator Peter O’Sullevan said: “It was a career of remarkable achievement. He will always be remembered for Red Rum and rightly so.”