Britain’s oldest manufacturing company is among a shrinking number of bell foundries to have survived as the demand for church tower bells has declined.

But this year workers at Whitechapel Bell Foundry are being kept busy after landing two major contracts for bells for both the Queen’s Diamond Jubilee and the London Olympics.

Established in 1570, during the reign of the first Queen Elizabeth, the company can lay claim to some of the world’s most famous bells such as the 13.5-ton Big Ben, the largest bell they ever cast, and the Liberty Bell, the symbol of American independence.

The bell the company has designed for the Games opening ceremony, being overseen by Slumdog Millionaire movie director and Mile End resident Danny Boyle, is at 23 tonnes the world’s largest harmonically tuned bell and the heaviest in Europe.

The bells is so large that Alan Hughes, who manages the business with his wife Kathryn, doesn’t think it will fit through the doors of the Whitechapel Road factory. It is therefore being cast in Holland.

But the couple revealed they are casting the hammer, which they believe will make the bell ring “at the start of the ceremony to welcome the world to London”.

Alan is the fourth generation of his family to run the business after his great-grandfather took it over in 1904. Kathryn came to work at the foundry while studying music, which is how the couple met and married.

Together they have kept the company going as hundreds of others have folded as the demand for tower and music bells has declined.

Standing among furnaces, lathes and gigantic pulleys on the factory floor Alan said: “The medieval recipe for bells is still the same. You have to create a void, the void has to be the exact shape and size, and you then pour metal liquid into the void.

“Making the pattern is just like being at the seaside with a bucket and spade. What you got is compressed sand moulded around a pattern.”

But it’s a skill which takes years to perfect, Alan explained. However, with other companies folding the couple have no problems recruiting staff.

Kathryn said: “Demand for bells is lower than ever and the trouble with bells is that they last for hundreds of years. But this year is a bit of an artificial peak because of the Jubilee.

“Bells are often used for celebration, it’s a great way of marking something. We made a lot of bells for Queen Victoria’s Diamond Jubilee.

“I think there are times when our history helps us get the jobs.

“This year, with the Olympics, we have two very valuable ones. But the turn over is the same because we can’t do anything else while working on these jobs. In other years we might do 20 smaller jobs in the same time.”

The couple are under strict instructions to keep the details of the Olympic bell secret and said they haven’t yet been told where in the Olympic Park it will be located.

Kathryn said: “We understand the idea is for the bell to start the whole thing off to welcome the world to London which is quite an honour. But the truth is we don’t know. It’s massive bell that’s all I can say, even the hammer is massive.

“Danny Boyle was one of the first people who came here and said this is what I want.

“He’s a nice chap and his enthusiasm for bells and the Olympic bell has been quite pronounced.

“The opening ceremony is the start of the show and across the world the success of the Olympics are judged on that moment so it’s fantastic for us to be part of that.”

The company is opening its door for self-guided tours during this summer’s Olympics.

During the two weeks of the Games, half of their 23 staff, which include moulders, general engineers, blacksmiths, bell turners and bell hangers, will each gets a week off to avoid travel and delivery problems.

Instead production will be cut back allow visitors into the workshop.

Kathryn said: “We are covered for whoever turns up. It’s self regulated because the queue will just get longer if people take longer to get round.

“Hopefully local people who wouldn’t normally come, and people from all over the world will come. Our Saturday tours are fully booked for the rest of the year so it’s the only chance to see our workshop this year.”

The couple have two daughters, who both study at the Royal College of Music, and who live in the flat upstairs from the bell foundry.

Kathryn said: “They have a very real interest and are very proud of the company. They will inherit it and it will be up to them what they do with it.”