The family of Henry "Chippy" McNish, the Glasgow-born shipwright who made possible the epic open-boat voyage of polar explorer Sir Ernest Shackleton, wants a posthumous award of the Polar Medal.

McNish - who later settled in New Zealand - helped to save the lives of the expedition's 28 men, but Shackleton branded him a troublemaker and refused to recommend him for a Polar Medal, an accolade given to most of the explorers in the failed Imperial Trans-Antarctic expedition of 1914-16.

Andrew Leachman, of the Antarctic Society of New Zealand, told London's Sunday Times newspaper at the weekend that the expedition was viewed as one of the greatest epics of survival.

"Shackleton even conceded they would not have lived but for McNish," Mr Leachman said.

"By withholding the Polar Medal, Shackleton achieved the final shaming of McNish and displayed a vindictiveness that fell below his own mercurial standards of loyalty.

"Had McNish possessed diplomatic skills to match his craftsmanship, he would have received the medal".

Instead, McNish died in New Zealand and, virtually unknown back in his former homeland of Scotland, was buried in a pauper's grave.

The plot at Wellington's Karori cemetery remained unmarked until the Antarctic Society erected a headstone in 1959 - misspelling his name as "McNeish".

Two years ago the society spruced up his final resting place and raised $6000 for a statue of McNish's beloved cat Mrs Chippy to go on the grave. Shackleton ordered Mrs Chippy shot when the expedition had to abandon its ship, the Endurance, in pack ice.

Shortly before his death in 1930, McNish was visited in a Wellington old people's home by an Antarctic historian who later said: "He lay there repeating over and over again: 'Shackleton killed my cat'."

Now, nearly a century after the expedition, the forgotten hero is the subject of a campaign by his Clydeside family to have the Polar Medal awarded posthumously.

"Chippy's family have kept his memory," John McNish, the explorer's great nephew, said.

Vincent Gillen, the curator of an online exhibition on McNish at the McLean Museum in Greenock, Scotland, has started a petition to have McNish's exploits recognised.

"We hope to correct an injustice which consigned a great man to oblivion through the pettiness of a man who regarded himself as great," he said. (See below for a link to the website.)

Wellington author and former journalist John Thomson said in his 1998 book Shackleton's Captain, on New Zealander Frank Worsley, that Shackleton threatened at one point to shoot McNish when he argued that the sailors no longer had to take orders because their contract, the Ship's Articles, had lapsed when the Endurance was crushed and sank on November 21, 1915.

Thomson noted Shackleton wrote in his diary that he would never forget McNish's stance at a time of stress.

"He didn't," wrote Thomson.

"He paid (McNish) back when he had the opportunity."

Shackleton also resented McNish's objections that attempts to haul three lifeboats from Endurance would cause irreparable damage.

Shackleton did not forgive the Scot for challenging his authority, even though he came to the same conclusion himself two days later.

The explorer's cousin, Jonathan Shackleton, said the confrontations cost McNish his medal.

"Shackleton's authority was questioned, which he would regard as a breach of loyalty.

"McNish's contribution was vital, but he threatened unity. Shackleton would have found that hard to forgive."

When the ice on which they were camped melted, the men were able to sail the three lifeboats to desolate Elephant Island, arriving in April 1916.

Three months later, Shackleton set out for the inhabited island of South Georgia, 1320km away.

Shackleton took five of the men, including McNish, and one of the lifeboats, the James Caird, to South Georgia and it was McNish's job to ensure the boat survived the voyage.

Without timber or tools, he modified the vessel, fitting sailing beams to the 7.6m craft.

He built in the bow and the stern and made the boat watertight with a caulking mixture of flour, water, artist's oil paints and seal blood.

McNish also used his skills as a tailor to keep the men well-clad and warm, and made boot crampons from brass screws and nails for a hazardous trek across South Georgia.

The boat reached South Georgia and within weeks Shackleton returned to pick up the rest of the team.

At the time, he conceded that without McNish's work, the men would not have survived.

"We certainly could not have lived through the journey without the James Caird," Shackleton said.

But the full extent of the enmity between the two men came in a letter Shackleton sent to the Polar Medal Assessment Committee in which he said of McNish, "NOT recommended".

The Sunday Times reported that nearly a century later it could prove impossible to redress the balance.

"Polar medals are rarely awarded posthumously because it requires second guessing," the newspaper said.

But a spokesman for the Scott Polar Research Institute at Cambridge in England, said: " If anyone deserved it, he did."

And Baden Norris, emeritus curator of Antarctic history at Canterbury Museum in Christchurch, said: "In my view he's the one man, even above (Captain Frank) Worsley, that saved the expedition.

"He made it possible for it to be saved (through) his expertise in building the boat."

Caroline Alexander, who wrote another book, Endurance, about the Antarctic expedition said: "Shackleton - very wrongly in my view - denied the Polar Medal to McNish, who was central to the success of the voyage."

McNish settled in New Zealand in 1925, where he worked on the Wellington waterfront until he was injured.

Poverty-stricken, he sometimes slept in a wharf shed under a tarpaulin but eventually went in to a charity resthome.

Despite his poverty, the New Zealand government provided him with a naval funeral.

- NZPA