More than 2,000 people took a once-in-a-lifetime opportunity to walk along the bed of an historic aqueduct yesterday.

In a UK first, a section of the 240-year-old Dowley Gap Aqueduct on the Leeds-Liverpool Canal near Bingley, which has been drained for repairs, was opened to the public.

The open day, hosted by the Canal and River Trust, was postponed from January 27, when it had to be called off because of bad weather.

And the decision paid off when bright sunshine brought out visitors in their droves.

The Grade II-listed structure, which spans the River Aire, is being drained so that any leaks can be mended, as part of the trust’s national £50 million spend on maintenance and construction.

Project manager Paul Brown said the works were going well, but revealed vandals had last week set the scheme back by damaging a pipeline being used to carry water along the canal while the aqueduct was empty.

He said: “Five million litres a day travel along it, but someone vandalised the pipe and it’s washed some of the embankment away.”

He said the project had insurance in place to cover the cost of the extra work, and the scheme, which began in January, was on course to be finished by mid-March.

He said he had been very pleased to see the crowds turning out to see the works in progress.

Mr Brown said the landmark had been a feat of engineering for its day.

He said: “As civil engineers, we still use these traditional techniques to reconstruct these things. It’s testament to how they’ve built it in the first place, and how well it has lasted.”

As well as walking along the aqueduct bed, the public could also climb into an empty lock, to see how the trust is replacing two sets of 3.5-tonne gates, which cost £30,000 each.

Construction supervisor Mark Overum said when the team drained the water, they found a couple of wallets, lots of mobile phones, some walkie-talkies and even a plastic pigeon at the bottom.