HUNDREDS of spectators and millions of television viewers watched a flypast by a Lancaster bomber yesterday to mark the 70th anniversary of the war-time Dambuster raid on the heart of industrial Germany.

As the RAF Battle of Britain Memorial Flight warplane swooped over Derwent Reservoir in Derbyshire, preceded by a Mark X1X Spitfire and followed by two Tornado GR4s from the 617 Dambuster Squadron, one prominent Scot recalled his family's role in the historic mission.

Lord Macfarlane of Bearsden spoke of how his brother, Richard, took part in the attack as a navigator in one of the 19 Lancasters which took off from RAF Scampton in Lincolnshire to destroy the dams of the Mohne, the Eder and Sorpe and flood the Ruhr Valley.

Richard Macfarlane, aged 18 when war broke out, had gone from the High School of Glasgow to Glasgow University and was studying for his MA, LLB when he volunteered for the RAF.

He was soon involved with Wing Commander Guy Gibson, who would lead the raid on May 16 and 17, 1943, and receive the Victoria Cross for his bravery.

The planes, armed with scientist Dr Barnes Wallis's bouncing bombs, flew to their targets either side of midnight and approached the dams at just 60ft before dropping their payloads.

"Richard was home on leave beforehand," said Lord Macfarlane, the entrepreneur, industrialist and philanthropist. "We gathered he was going back to do something special. But he couldn't tell us what it was.

"On the morning after the overnight raid we were listening to the wireless and heard the dramatic news. So we were pretty certain that was where Richard had been.

"They were given leave immediately and he was back at our home in Broomhill, Glasgow, sitting round the dinner-table and confirming he had been on the Dambuster raid that previous night. However, he was still obliged to say very little about it."

In fact, Richard Macfarlane and his crew were involved in a bizarre incident, in which his pilot was flying so low he struck the water before reaching his target and lost the bouncing bomb. The pilot, Geoff Rice, managed to regain the height and was among those who returned safely.

Richard went back to his duties and was on another mission over Europe later that year when his plane was shot down over Belgium. Pilot Rice survived but the young Macfarlane was among the six crew members who were killed.

Today, Lord Macfarlane's grandson, another Richard, is celebrating his 21st birthday. Along with his grandfather, he has visited his grand-uncle's last resting place at Charleroi in Belgium, as a piperplayed a lament by the graveside.

Yesterday's event was staged in the Hope Valley in Derbyshire because it was used by the airmen for practice runs in the weeks leading up to the raids. The Wallis bouncing bombs were tested in secret on Loch Striven, which is on the Glenstriven estate in Argyll, with locals evacuated from the area.

Of the 133 airmen who went on the raid – codenamed Operation Chastise and immortalised by the 1955 film starring Michael Redgrave and Richard Todd – 53 did not return. More than 1300 people are thought to have been killed when the Ruhr Valley was flooded.

New research suggests the loss of water caused by the dams' destruction had a far greater effect than many previously realised – from making firefighters powerless to put out the flames of British incendiary bombs to cutting vital German steel production due to a lack of water for cooling.