Britain's biggest water-powered cuckoo clock took three years and £20,000 to build 72-year-old Richard Pim constructed 25ft cuckoo clock in his back garden Britain's biggest water-powered clock features 3ft tall cuckoo Heretfordshire garden also features an igloo made of glass bottles and gargoyles modelled after the owner A 72-year-old amateur gardener has spent three years and £20,000 building Britain's biggest water-powered cuckoo clock - which is the size of a house. Richard Pim designed and built the 25ft tall clock, complete with a 3ft wooden cuckoo which pops out every hour and chimes with a huge pipe organ. It is powered by a complex system of cantilevers, counterweights and pulleys which convert energy from a passing stream. Mr Pim, who is a retired hydrogeologist used his experience to design and build the wooden structure at his water gardens in Herefordshire. Giant achievement: It took a total of three years and about £20,000 to complete the unique clock Proud owner: 72-year-old Richard Pim masterminded the project, and built most of the 25-ft tall clock by himself Wake-up call: This 3ft painted cuckoo is a scaled-up version of the birds that were designed for the original cuckoo clocks made in Germany's Black Forest He said: 'I think it's quite fun and rather beautiful. I wanted to make something that made people laugh. It took a while to build, but I did almost all the work myself. I had a local carpenter and local machinists help me with some of the frame and the metalworking though. Mr Pim's knowledge of complex water-powered structures comes from a long career spent bringing water to arid farmlands in Saudi Arabia and Nepal. He drafted in an organ-maker to help build the complicated mechanism that makes the bird cuckoo. The house uses pipes and bellows to create compressed air to pump through a music box, tuned to mimic the call of the bird. He said: 'It's gaining a few minutes every day at the moment. The warmer weather causes the wood to warp slightly and makes the water flow differently through the system of pipes and tanks. Picturesque: At almost 7m tall the cuckoo clock should be an eyesore. But the structure's quaint design and floral surroundings look like a fairytale scene No need for a watch: Richard Pim and his wife Sally will only have to glance out of the window to see the time in their back garden Sweet sounds: The organ pipes and music box used to generate the distinctive cuckoo call every hour. Mr Pim had help from a specialist organ-maker to build the clock's mechanism 'But no-one's setting their watches by it.' The clock is one of the attractions at Westonbury Mill Water Gardens, a three-and-a-half acre visitor garden. Mr Pim owns a granite tower with gargoyles modelled after his own head, and an igloo built out of glass bottles. His wife Sally said: 'Three years to build the clock is astonishing. I think it's amazing what Richard does, astonishing.' Mr Pim said: 'I'm going to keep on making them until I can't any more, I think. It's something I enjoy very much and it keeps me very busy, and happy. A garden needs some action. It's a great thing for kids to come and see the mechanism - to see how engineering really works.' Hard graft: Mr Pim had some help from local carpenters to complete his mammoth project, but did most of the work himself In the running?: The largest cuckoo clock in the world is said to be in Ohio. The world's biggest free-hanging cuckoo clock is in Germany