Amateur historian Malcolm Finebaum said the lesser-known of the pair had been the "main man" in the Czech capital, putting himself in harm's way on a daily basis while interacting with, and fooling, Nazi officials.
In December 1938, three months after Prime Minister Neville Chamberlain proclaimed "peace for our time" after agreeing to hand the Czechoslovakian Sudetenland to Germany, Sir Nicholas thought up the idea of transporting imperilled children to Britain.
Mr Chadwick had independently arrived in Prague at the same time to bring back two Jewish boys who had been sponsored by his school in Dorset.
The men were introduced to each other, and the course of history was dramatically altered.
Mr Finebaum said that after meeting Sir Nicholas, "Trevor was so impressed that he immediately offered to help and returned after escorting the two boys back to England".
He stayed in Czechoslovakia until the summer of 1939, performing what Mr Finebaum called the "acts of bravery and pure altruism" necessary for saving 669 children while at close quarters with the Nazis.
Mr Finebaum said the teacher had to gather photos of the children he and Sir Nicholas were looking to save so that families thinking of providing refuge in England could decide who they wanted to open their homes to.
In addition to these duties, Mr Chadwick ensured every child made it on to their train.
"The parents realised they were saying goodbye but had to pretend to the children it wasn't goodbye," Mr Finebaum said. "Trevor was the person everyone looked to at that moment to placate the children and get them on board."
Trains would leave sporadically, and the children had to be on them at the right time to meet their new foster parents in England. If the correct paperwork had not been filed by the time the children had to go, Mr Chadwick took a step that could have placed him in the firing line.
Mr Finebaum said: "He found a forger in Prague who supplied him with forged papers he could present to the Germans. He was at risk simply by getting papers forged, which is something most people probably wouldn't have done."
The 77-year-old historian explained that his research into Mr Chadwick's efforts was born from feelings of injustice.
He said: "It seems unfair to me that we see Winton as a hero, but no one's heard of Trevor Chadwick."
Mr Finebaum emphasised that his work was not intended to take anything away from Sir Nicholas, who he called "a most remarkable man - truly an outstanding individual who never sought the fame that came his way".
Sir Nicholas himself had always said there were other individuals who had put themselves in greater danger and were more deserving of the credit that came his way, Mr Finebaum said.
"I just want people to know the name of Trevor Chadwick as well as they know Nicholas Winton," the historian said.
"That's my only motivation. I feel that something ought to be done for the guy who put his life at risk and has never had any recognition for it."
