A little-known, but vital cog in the machinery of international telecoms arrives at the Science Museum in Wroughton.

A giant piece of engineering history will soon take pride of place on show at the Science Museum in Wroughton after it was donated to the institution by BT.

Measuring eight metres long and 11 metres high, the enormous Rubgy Radio Station tuning coil once formed an integral part of the most powerful telegraph transmitter in the world.

Delivered on January 5 to the Science Museum’s Wiltshire-based large object store, the donation is part of BT’s commitment to preserving its heritage, which includes the web-based Connected Earth project.

"The Rugby tuning coils are a wonderful, almost monumental reminder of worldwide radio communications in their early pioneering days," said John Liffen, curator of communications at the Science Museum.

"We're delighted to be receiving this awe-inspiring equipment from BT and we're looking forward to showing it in a re-assembled state at Science Museum Wroughton later in 2005."

John Liffen (left), curator of communications at the Science Museum, and David Hay, head of corporate memory for BT, with sections of the tuning coil.

Comprising six copper coils each measuring five metres in diameter and weighing 350 kilograms, the artefact resembles a vast spider’s web and as part of BT’s Rugby Radio Station played a key part in international communications.

The coil was part of the tuning circuit used to tune the antenna to the right operational wavelength and carried up to 1,000 amps of radio-frequency current. It formed an integral part of the high power very low frequency GBR transmitter, which first began service on January 1 1926 and was at the time the most powerful telegraph transmitter in the world.

The vast apparatus in action at Rugby Radio Station during 2004.

Although the original tuning coil was destroyed by fire in 1943, its replacement, which will now form part of the collection at Wroughton, helped continue GBR’s vital work during the Second World War.

Operating ‘behind the scenes’, the transmitter enabled communications with the Royal Navy and the French Resistance through the war years. This military role continued during and following the Cold War when encrypted data was transmitted to ships and submarines.

Decommissioned in March 2003, a team of six engineers dismantled the tuning coil in December 2004 before moving it to the Science Museum’s large object store in Wroughton.

The tuning coil is carefully dismantled at Rugby Radio Station in the midlands.

Part of the UK-wide Connected Earth network, established by BT in 2002 to make its heritage collection accessible to the public, the Science Museum at Wroughton is a particularly appropriate location for the coil; the original receiving station for the early transatlantic telephone service, operated from Rugby Radio Station, was built there.

"This is a fascinating and historic piece of telecommunications apparatus, part of the equipment which was once the hub of the UK’s international communications system," said David Hay, head of corporate memory at BT.

"We felt it was crucial to preserve it for future generations so that they can learn about its once vital function in the country’s communications infrastructure."

It is hoped the coil can be put on public display in spring/ summer this year.