The rescue of the crew of the Green Lily 20 years ago today is remembered as one of Scotland's most tragic feats of bravery at sea.

A powerful storm had swept into Shetland on the weekend of November 19, 1997, and whipped the sea into a frenzy.

Ferry sailings were cancelled and bridges were closed as 50ft waves battered the islands.

But it was into these conditions that the Green Lily sailed.

The RNLI received its first call about the cargo ship shortly before 9am when its engine failed 15 miles south of Shetland.

Despite the storm the situation appeared to be under control and two nearby tugs, the Tystie and the Gargano, were sent to bring her to safety.

During their journey back to port, however, the line between the Tystie and the Green Lily separated and the 3000-ton cargo ship began to drift.

The RNLI immediately dispatched its Lerwick lifeboat and the coastguard scrambled a helicopter, while the Tystie desperately tried to re-establish a tow.

The Lily was now less than a mile offshore with no engine and RNLI coxswain Hewitt Clark realised that despite the danger a rescue attempt would have to be made.

The crew of the lifeboat tried repeatedly to bring it alongside but each time they did their boat was slammed against the hull of the 3000-ton vessel.

They eventually managed to bring five members of the crew aboard, hauling them over the ship's rail, before being forced to retreat 600ft from shore.

By then the Green Lily had stabilised and the coastguard helicopter was able to move in and lower winchman Bill Deacon onto the deck.

The 50-year-old helped ten men to safety before a huge wave washed him overboard and he was lost into the raging sea.

His towline was still attached and his crewmates were forced to make the agonising decision to cut the cable after it snagged and threatened to endanger the helicopter.

Meanwhile, the crashing waves forced the RNLI to return to shore or risk endangering the men they had rescued.

The Green Lily could not be saved and was swept onto the rocky shoreline and destroyed.

Bill Deacon's body was recovered the next day and he was posthumously awarded the George Medal.

Hewitt Clark received the RNLI's highest honour, the Gold Medal, an accolade which has not been handed out since.

On Sunday at midday, a wreath will be laid at the site of the grounding by the local lifeboat team, followed by a service in Lerwick.

Recalling the rescue two decades on, former team member Magnus Shearer said: "All rescue services that day were truly outstanding.

"When Hewitt was taking the lifeboat alongside the vessel if anything had gone wrong at any point I feel sure we would have lost the lifeboat and very possibly all the crew.

"There was absolutely no margin for error. I'm very proud of Hewitt and very proud of our crew and I think they're a tremendous credit to the RNLI and everything it stands for."

An inquiry which followed the grounding put part of the blame on the crew of the Green Lily and their decision to sail on November 18.

They were slow to take action after the ship got into difficulty and some of their actions hindered their rescue.

Often nobody was at the rail when the lifeboat pulled alongside and in one instance a survivor could not be lifted in because he was carrying his luggage.

However, the inquiry acknowledged that the extreme weather had hampered the crew's ability to save the Green Lily.