Our interest was further piqued when we watched Kristin Scott Thomas discovering her Grandparents' War in the series shown by SBS, learning the harrowing experiences of her grandfather's eight convoys as a destroyer captain, and getting him his posthumous Arctic Star.

We'd always known our late father Hugh McDonald had served on one convoy. His leather satchel of old photographs had one of him on the open bridge of a warship, bundled in woollens, a duffle coat and balaclava, drawn and weary-eyed, against a backdrop of ice-covered sea.

As boys, our father had told us of trying, once arrived in the bleak port of Murmansk on Russia's northern coast, to persuade a Soviet Army sentry to swap his enamel red star cap-badge, in vain. His ship, he told us, was called HMS Bulldog.

Where to pin down detail to support an application for the Arctic Star in his memory? His service record, downloaded from the National Archives of Australia, was a very bare record of successive ship and shore-training postings. The only mention of the Bulldog was a single-line entry: Orlando (Bulldog) 27.1.42 to 26.5.42.

Only seven months earlier, Hugh had been commuting by ferry across Sydney Harbour from his Neutral Bay boarding house to his job at the Bank of New South Wales in Martin Place.

Then his call-up arrived. Japan had not yet entered the war, so after basic training, he and other Australian volunteers sailed through the Panama Canal to join the Royal Navy for further officer training, then a ship posting as a provisional sub-lieutenant.

Orlando, we discovered, was the naval dockyard on the Clyde River near Glasgow. Reporting there, and going aboard HMS Bulldog, was the start of an extreme sea-test.

The Bulldog had already earned its place in the history of the Second World War, though this remained a secret for decades. In May 1941 it had forced a U-boat to the surface and a boarding party had retrieved its Enigma cypher machine and code-books, greatly helping the cracking of German signals at Bletchley Park that produced the "Ultra" stream of intelligence.

Setting out from Scotland, the Bulldog spent the early winter months of 1942 shepherding ships around the Faroe Islands and Iceland. On April 14, 1942, it led three other destroyers to join the convoy PQ 14 heading for Murmansk, in northern Russia.

With Hitler's attack on the Soviet Union in June 1941, the Russians were suddenly British allies desperately in need of munitions. The shortest route for them was the 1700-nautical mile arctic route from Iceland to Murmansk, in the Kola inlet, or ice-permitting, to Archangel.

To cut this supply line, Nazi Germany shifted U-boats, aircraft and its major surface warships, including the battleship Tirpitz to bases in the fjords of occupied Norway. It was a constant nightmare for British fleet commanders that these ships would spearhead another breakout like that of the Bismarck earlier in the war.

The German submarines lurked under temperature layers caused by mingling of warm Gulf Stream with cold, less saline ice-melt, layers that bounced off the pings from the asdic (sonar) of the Allied destroyers above. Condor aircraft circled out of anti-craft gun range, relaying convoy positions for waves of bombers.

The 115 days of perpetual darkness in winter helped hide from the enemy, but increased the danger of collision for ships running without lights. The summer brought 24 hours of daylight - and round-the clock attack for heavily laden merchant ships and tankers plodding along at eight knots.

As well as this gauntlet of fire, convoys faced an endless succession of gales, whipping up spray that froze on upper decks, risking capsize for smaller ships. The water temperature rarely rose above 8 degrees. Sailors forced to abandon ship died within minutes unless quickly rescued. In many cases, ships could not stop to pick them up for fear of becoming torpedo targets too. Over 1941-45, Allied navies lost 1944 men, and the merchant marine 829 of its sailors on the "Kola Run".

We found a short account Hugh had written for the magazine of his old school, Caulfield Grammar in Melbourne, in December 1942, short on operational detail and sparing the boys the fear and death:

"We ploughed along with ice all over the decks, with icicles hanging from the guard rails, masts, guns, funnels, in fact from everything. Inside where we ate and slept, the ice was an inch thick on the hull, and the bulkheads and deckheads. Outside, clear weather alternated with blinding snow storms, and the spray thrown up from the forecastle froze in the air and beat against one's face in the form of ice. There was no question of keeping really warm; it was just a matter of not becoming too cold. Icebergs were frequently sighted, and sometimes the sea for miles around was covered with ice floes."

The PQ 14 convoy had been in trouble as soon as it sailed from Iceland on April 8. Four days of storms and floating ice forced 16 ships to return to port with damage. The Bulldog escort flotilla, and four smaller corvettes, took charge of the remaining eight ships, joined by the light cruiser HMS Edinburgh, which was taking steel plating to repair another British cruiser.

Even with this protection the convoy lost its lead merchant ship to a U-boat's torpedo. From five days out of the Russian ports, convoys came within range of German bases in occupied Norway. "It's quite a picnic," Hugh wrote. "Jerry uses everything up there, and we ran into high-level bombers, dive-bombers, torpedo-bombers, submarines and surface craft."

It was like a game of chess with the U-boats, he wrote, "they manoeuvring to get at the convoy, and we making depth-charge attacks whenever the submarines appeared to be dangerous. Now and again the subs would get fed up and let one go at us, but a destroyer on a zig-zag is hard to hit."

Long-forgotten war histories in the State Library filled out the story of PQ 14. It reached Murmansk on April 19. Two days later Hugh might have celebrated his 26th birthday with fish, bread and vodka in the Soviet Navy's mess. Then on April 28, the Bulldog and other warships set out back to Iceland with the return convoy QP 11, the Edinburgh ranging ahead in a high-speed zig-zag.

A Condor spotted them on April 29 and U-456 positioned itself ahead. On April 30, its captain, Max-Martin Teichert, made a deft calculation of the Edinburgh's position and fired a spread of torpedoes that hit the cruiser in two places. Two British and two Soviet destroyers raced up to screen the Edinburgh as it attempted to make it back to Murmansk with speed down to three knots and requiring a tow for steering.

The rest of the convoy ploughed on, with sea ice forcing it closer to Norway than planned and slowing its speed. At 5.40am on May 1, Heinkel bombers arrived to make the first German aerial torpedo attacks of the war, but were beaten off. Then at 1.40pm the escort spotted three German destroyers racing for the convoy.

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The three attackers - Hermann Schoemann, Z.24 and Z.25 - were big, more like light cruisers than destroyers, heavily armed with 15-centimetre (5.9-inch) guns. The four British destroyers - Bulldog, Beagle, Beverley and Amazon - were a little over half their tonnage and armed with less powerful 4.7-inch and four-inch guns, and only two or three of them per ship, as guns had been sacrificed to fit more anti-submarine depth charges and mortars.

Even so, Bulldog's captain, Maxwell Richmond, ordered the four destroyers into line ahead at full speed towards the German flotilla. At close range, the opposing groups veered off and loosed broadsides of gunfire and torpedoes at each other. A torpedo track passed close astern of the Bulldog. A German shell hit the Amazon in the wheelhouse, requiring its crew to steer by adjusting the speed of its two propellors.

The Germans attacked three more times, with Richmond swivelling back in response, firing and laying smoke-screens. On the third attack, German shells straddled the Bulldog, hitting it with metal splinters. But Richmond's aggressive tactics succeeded. At 5.45pm, the German ships peeled off. From HMS Beverley, an officer flashed a signal to Richmond: "I should hate to play poker with you."

The convoy proceeded without further loss, reaching Reykjavik on May 7. But another drama had unfolded in its wake. After breaking off the attack on QP 11, the three German destroyers headed east to finish off the Edinburgh, which they reached on May 2.

The stricken cruiser cast off its tow and got up to its best speed of eight knots. With steering out, it was locked in a circular course, but blazed away with its one remaining gun turret, crippling the Hermann Schoemann, while its two escorting destroyers Forester and Foresight raced to attack the Z.24 and Z.25, both getting badly damaged.

A torpedo then hit the Edinburgh, nearly breaking it in two. British minesweepers took off its crew, then attacked the German ships with their single four-inch guns. Mistaking them in the poor visibility for a new force of destroyers, the Z.24 and Z.25 broke off the engagement, rescued the crew of the Hermann Schoemann, sank it, and withdrew. With its last torpedo, HMS Foresight then sank the abandoned Edinburgh, and the escorts limped back to Murmansk.

Known only to a few senior officers, the Edinburgh had been carrying 4.57 tonnes of gold bullion, part of Joseph Stalin's payment for British munitions. The treasure lay in 245-metre deep water north of Norway until a British salvage operation retrieved all but five of the 465 ingots over 1981-86.

Hugh had left the Bulldog after this initiation of fire for further training. The same musical ear that had got him a scholarship to Caulfield Grammar was spotted as a key attribute for an asdic specialist.

But this was not his last encounter with the German destroyer Z.24. On June 9, 1944, he was aboard HMS Eskimo among other British, Canadian and Polish destroyers screening the D-Day landings in Normandy. At 1am that day, the Z.24 with two other destroyers and a torpedo-boat came up from the Bay of Biscay to disrupt the landings. Alerted by Ultra, the Allied destroyers intercepted them off Cape Ushant, sinking one and forcing the others to flee.

On June 24, Hugh's insistence on the genuineness of an asdic contact led to the sinking of U-971 and the capture of all but one of its crew. For this he was awarded the Distinguished Service Cross. In early 1945 he went back to the Australian Navy, and service in the Philippines aboard HMAS Nizam, seeing kamikaze attacks on nearby ships, and in Tokyo Bay for the Japanese surrender.

Then he went back to work in the bank, where he stayed to retirement. He died in 1985.

We put in the results of our research to the British Defence Ministry, who referred us to the Australian Department of Defence. In January, the Arctic Star arrived for our father: a six-pointed copper-zinc star with King George VI's emblem, and a ribbon with stripes of dark blue (for the navy), light-blue (for the air force) and red (for the merchant navy) around a central stripe of white, for the ice.

It's one of 94 Arctic Stars awarded to Australians who served in this "cold corner of hell".