See inside the workshop at Stanley Ferry where the country's largest lockgates are built

The “beating heart” of the Canal and River Trust, the workshop on the Aire and Calder, next to the landmark aqueduct, is where the largest of the replacement gates are made for 2,000 miles of canals and rivers in England and Wales. Close up their sheer scale is surprising.

Last year the workshop turned out £100,000 6m by 6m gates for the River Trent at Newark. They were so large they had to be dismantled once they were built in the workshop and reassembled outside in the car park, before being ferried down the canals to Newark.

Visitors tomorrow will see gates in various stages of production and the machinery they use in the workshop.

There will also be a chance to see the vast dry dock where boat repairs were once carried out.

National workshop manager Simon Turner says there’s a “bow wave” of replacements coming their way as lock gates last refurbished in the 1990s come to the end of their lives.

Over the next few years they will steadily build up production from 140 to 220 leaves (leaf is the name for one side of the lockgate) a year.

The lock gates are built bespoke by the CRT and each is different, although the techniques for building them haven’t changed much in the last 200 years.

Mr Turner said: “As the canals developed they were built at different times by different engineers in different parts of the country and they had their own design and how they should look and operate.

“The heritage is hugely important to the CRT and we make them on a like-for-like basis. Lock gates in the North-East will be different to those in the South-East.

“Because they are 200-year-old structures they may shift, subside; their dimensions are never consistent.”

Locks can either be narrow or broad – the latter is twice the size of the other and allows two boats to pass.

Mr Turner said: “Some canals were actually moved from being narrow to broad, the Grand Union from Birmingham to London was widened in the 1920s and 30s.

“The reason why we do the largest gates at Stanley Ferry is that there’s higher headroom.”

Most of the gates are built of British oak – Mr Turner says it is “rare” now that they use tropical hardwoods.

“There are other timbers that would be as good or potentially better like opepe but the sustainability of that is not what we have got with oak.”

He says greenheart from Guyana and Suriname is much stronger, but less sustainable and hugely expensive.

The invasion of Ukraine has seen timber costs shoot up by 25 to 30 per cent.

"It has become hard to source the sections and sizes we need,” added Mr Turner.

"In terms of the joinery it is mortise and tenon joints, that style of joint hasn’t changed, it’s the strongest joint for that type of construction. Right back in the day it would have been cut by hand and now we use machines.”

Everyone in the team has served apprenticeships as carpenters and joiners – but even someone who is experienced in their trade will still take a couple of years to get up to speed.

Ex-primary school teacher Michelle Lund Conlon, inset, is the trust’s first female apprentice carpenter and joiner at Stanley Ferry, which is three miles from Wakefield.

Mr Turner said he hopes today’s open day will show people how much effort goes into keeping on top of maintaining the canal network.

“I am a builder and a joiner by trade and when I go and look at the structures on the canals you know how hard they are to build now given all the technology and equipment we have now.

"When they did it 200 years ago everything they did was by hand, the canal was dug by shovels not excavators, cutting large sections of timber was done by handsaws. I just go ‘wow’ – how skilful and how committed these people would have been.

"They wouldn’t have been people earning the sort of money the trades get these days. A manual worker was low paid. It is absolutely awesome and blows me away still.”

There will be limited spaces for people wanting to take a tour tomorrow between 10am and 4pm.