Relief came on February 15 when police told Colonel Seymour they had recovered the collection, which included nine Victoria Crosses belonging to the likes of Charles Upham, Keith Elliott and Clive Hulme.
But he was still angry the thieves had not been caught and was anxious for the medals to be returned to "their rightful home".
Then, driving back from work one evening, he felt an excruciating pain in his belly, and collapsed.
He was rushed to hospital, where doctors found a tumour in his pancreas and ordered the 61-year-old to go home and, in his words, "get my affairs in order".
The tumour has since shrunk and Colonel Seymour is feeling "95 per cent", determined he will not be beaten by cancer - the same disease that killed his first wife and left his son fighting for his life.
He was also relieved in October to learn of the arrest of two men for allegedly stealing the war medals, and then, a few days later, to see the irreplaceable collection restored to the museum.
Families of the medal recipients were among those who attended a "marvellous" ceremony on October 21, and Colonel Seymour said the emotion of the occasion, which involved young Army recruits forming a guard of honour, was overwhelming.
He has also watched with joy as thousands of visitors have flocked through the doors of the newly secure museum to view the medals since.
"There has been a silver lining of this very, very dark cloud," he said.
Colonel Seymour expects the crowds to swell during the summer holidays, and hopes visitors will take the time to look at other exhibitions, particularly a new one focused on New Zealand soldiers in World War I.
The Last 100 Days: Victory and Home exhibition takes visitors through a wood-lined trench while a smell mimicking mustard gas fills the air.
Colonel Seymour said the courageous deeds of World War I soldiers had been overlooked and the exhibition was designed to raise awareness of how those New Zealanders helped to bring about the war's end.
Dressed in his uniform with his own set of eight medals, the Vietnam and Malaya veteran said he was still angry at the "despicable act" of those who plundered the Valour Alcove, but had always been confident of arrests because the country's four million people were also horrified.
"I'll be angry for the rest of my life but it will dissipate as new milestones are met," he said.
The two suspects, whose identities are suppressed, are due back in court on January 12.