But now, almost a year since it disappeared, Mr Sykes has still not seen the badge.
He is dejected at the prospect of attending this year's Anzac Day service without it and has made another plea for help to find it before commemorations begin on Friday.
"It's got more value to me than it must have cash-wise," he said yesterday.
"It's just family value and we would like it back."
Mr Sykes believes the young man in uniform who took the badge from the boy may not have realised its significance.
"I'm inclined to think that he mightn't even have looked at it properly and seen what it was, and just put it in his pocket, and forgot all about it."
Mr Sykes does not have a photo of the badge and has been thwarted in attempts to obtain a replica because the badges are so rare.
He said neither the RSA or Waiouru Army Museum had been able to help him, even with a photo.
The first New Zealand Gallipoli Association badges were issued in 1916.
Mr Sykes is not sure when his father received his badge, but the family still has his Gallipoli Medallion.
The large, two-sided medallions were awarded to all Gallipoli veterans in 1967, but Mr Sykes' father, Corporal Percy Raymond Sykes, did not receive his before he died the same year.
Corporal Sykes served in Gallipoli with the New Zealand Expeditionary Force in 1915. He landed on the Turkish peninsula on August 9, but was placed on a hospital ship a week later when he became ill.
Mr Sykes said the illness was unspecified on his father's war records, but was likely to have been dysentery, which afflicted many soldiers.
Corporal Sykes was sent to Cairo in Egypt to recuperate, and served in Germany before returning to New Zealand on May 13, 1919.
THE BADGE
* New Zealand Gallipoli Association lapel badge
* Round and 14mm to 15mm in diameter
* A golden cream colour with a Turkish crescent moon and star on the front
* Different from the 75mm Gallipoli Medallion issued to veterans and their families in 1967 which features a picture of a soldier leading a donkey
Online link: The Auckland War Memorial Museum has a Book of Remembrance on its website for people to post messages on to remember those who served and died in war.