Computer experts in the United Kingdom has successfully restored one of the earliest computers assembled by man, firing it up anew Tuesday this week to relive the infant moments of a device that has undergone radical transformation.

According to Kevin Murrell, trustee for The National Museum of Computing (TNMOC), he unearthed the Harwell Dekatron, also known as the Wolverhampton Instrument for Teaching Computation (WITCH), at the Museum of Science and Industry in Birmingham.

The hulking computer relic, which media reports said is the size of a regular house garage, pricked Mr Murrell's curiosity and prompted him to dig more.

He discovered that the 2.5-tonne machine was first used in 1951 by the Atomic Energy Research Establishment in Harwell but was retired after only six years of service.

WITCH was mainly employed "to take the tedious but necessary work of performing calculations away from the mathematicians and let them think about the big picture," Yahoo! News reported on Wednesday.

It was prized then as an accurate computation tool for atomic scientists but its sluggish humming easily made the Harwell Dekatron obsolete and its utilitarian value was eventually redefined as a teaching aid, a role that according to PC Pro lasted until 1973.

During its prime, "the Harwell Dekatron was one of perhaps a dozen computers in the world, and since then, it has led a charmed life surviving intact while its contemporaries were recycled or destroyed," Mr Murrell told TechNewsDaily.

It was only fit to restore the WITCH, he added, which took three years to complete though TNMOC experts who were involved in the effort got just what they needed - the machine's all original parts and schematics plus much needed guidance from two of the original developers.

PC Pro identified them as Dick Barnes and Ted Cooke-Yarborough.

But even with all the pieces falling into their proper places, the restoration work was not exactly a walk in the park, TNMOC volunteer Delwyn Holroyd told TechNewsDaily.

"The restoration was quite a challenge, requiring work with components like valves, relays and paper tape readers that are rarely seen these days and are certainly not found in modern computers," he shared.

Once the WITCH was powered up anew, the monster calculator spawned a sound that The Huffington Post said is akin to "a roomful of typewriters." The machine's calculation muscle rests mainly on its "10 gas-filled tubes that can each be activated as part of its decimal counting system."

This behemoth is a power-hog, TNMOC experts said, requiring more than 30 times the electricity required to energise modern computing devices.