No one can accuse youngsters at a leading state school of bad time-keeping.

Pupils at Altrincham Grammar School for Boys have put the finishing touches to their own pendulum clock after months of painstaking work. The boys learned centuries-old skills to build the 70lb mechanism, fashioning cogs, gears and springs from scratch. The timepiece will mark the school’s 100th anniversary next year.

Working under the guidance of school technician Garry Binns, the seven pupils used metal-working skills to pound and cut the brass and steel parts to shape. And their next task will be creating a handsome oak and glass case for the clock – which they will do once again from scratch, using traditional methods.

The completed clock, which requires winding once a year, will take pride of place at the school next year. Mr Binns said the clock was modelled on the elegant ‘skeleton’ clocks found in 18th century France.

He said: “Our aim is to create a clock that is close to perfection, particularly in terms of its time-keeping and design. This means ensuring that each part is manufactured to an extremely accurate specification. If something is not right, even by a tiny fraction, the clock may not work effectively.

“All the boys have been working hard to ensure the components are absolutely precise, right down the to smallest bolts and screws.”

If properly maintained, it could last for more than a century, he added.

Tim Gartside, the school’s headteacher, said staff were amazed by the work of the pupils, who worked on the project during evenings and weekends.

He said: “The design and manufacture of the clock entirely within school has given us a tremendous opportunity of providing pupils with practical experience of traditional engineering and craftsmanship techniques.”