It was a week-long military exercise in the Mediterranean, designed to bring two forces together.

But when the Italian paratroopers boarded an RAF Hercules from Wiltshire in November 1971, it became a tragedy that formed a bond lasting 37 years.

For this week at a windswept chapel in Livorno, Italy, a standard was presented that reaffirmed the bonds between one of Italy's famous 'lightning' paratroop brigades and the RAF base that is home to Britain's Hercules fleet.

That simple gesture was also something of a first for the RAF too – never before has one of their standards been laid up outside the Commonwealth, and never before in a Roman Catholic church either. But the party of officers and airmen from RAF Lyneham were continuing to cement the bonds of grief that have lasted between the two military forces for more than a generation.

In the early morning of November 9, 1971, RAF and Italian paratroopers embarked on a training exercise designed to test their capabilities but also bring two friendly forces together. The aim was to fly from the mainland at Pisa and drop Italian paratroopers onto Sardinia. It was the fortnight President Nixon began ordering troop withdrawals from Vietnam, Cambodia was falling to the Khmer Rouge and the UK Parliament voted to join the EEC.

Eight Hercules from Lyneham took off that morning, but 20 miles or so out at sea, for reasons unknown, one of the transport planes crashed.

The cause has never been established – either there was catastrophic engine failure, or the plane had exploded before it even hit the water.

The four-man crew from the Wiltshire base died, along with 46 Italian paratroopers, sitting in the belly of the aircraft waiting to jump over Sardinia.From that day on, XXIV Squadron at Lyneham – the RAF's oldest – and the 187th Brigade of the Folgore paratroop regiment have been inextricably tied.

And so, when the RAF squadron's standard – the flag and emblem – was retired earlier this year, there was only one place they wanted it to be laid up. All the old standards from the various squadrons at RAF Lyneham end up in the village church, but this time was different.

"The standard was presented to the squadron in 1981 by the Princess Royal and has come to the end of its life," explained a spokeswoman from RAF Lyneham.

Sqn Ldr Jon Edmondson said the standard was more than just a flag. "It represents the faith and trust our Sovereign has in our squadron," he said.

"In turn the laying-up of our retired standard in the chapel of the 187th Folgore Regiment demonstrates the close relationship and trust that exists between our two units and our two countries.

"It is a fitting acknowledgement of the sincere and moving recognition that the regiment has shown to the members of the XXIV Squadron crew who perished that day."