Four giant structures that have dominated a skyline for more than 50 years were demolished in a series of thundering explosions in front of hundreds of spectators on Sunday morning.

Controlled blasts levelled three 318ft (97m) cooling towers and a single 416ft (127m) chimney stack at the decommissioned Richborough power station at Richborough, near Sandwich, Kent.

A siren sounded and a warning rocket was fired one minute before the explosions to scare off birds and alert spectators watching from beyond an exclusion zone.

Within 20 seconds of the explosives detonating at 9am, the concrete structures were reduced in sequence, one by one, to thousands of tonnes of rubble, ending with the chimney.

Some locals had campaigned to keep the towers, saying they formed part of the historical landscape and were used as a navigation point by fishermen.

But their demolition, set off by explosives engineer Holly Bennett, now clears the way for redevelopment of the 300-acre site.

Among those to mourn the destruction of the local landmarks was 83-year-old John Jones who helped build the chimney from 1960 to 1961.

The great-grandfather recalled how he and his fellow workmen threw half a crown into the chimney after the first part of it was built, and another one just before it was finished.

Mr Jones, who lives in Broadstairs, said: "We did it to ward off bad luck. It's sad to know it has gone because it brings back a lot of fond memories of when I was young.

"It was a sad part of my life as well because my mother died around the same time it was built and the chimney always reminds me of that point in my life.

"It was the hardest construction job I had ever been on. We worked seven days a week mostly, putting in 10 hour days and sometimes more, for a year.

"I was young then and I could go like mad. As a youngster I wanted to stand out from the crowd and do things in life. I thought this would be exciting. It was but it was also really hard work."

The power station site has regularly been used as a film location since its closure in 1996, most recently in the 2008 comedy-drama film Son of Rambow.

It was built by the Central Electricity Generating Board in the late 1950s and early 1960s, and entered service in 1962 as a 342MW coal-fired station, using coal from Kent and other coalfields.

It was converted to oil in 1971 and has remained largely vacant since being decommissioned in 1996. It underwent asbestos removal and partial demolition, which ended in 2000 but the cooling towers and chimney have remained - until today.

The demolition, which followed nearly two years of planning, now paves the way for the current owners, Richborough A Ltd and development managers BFL Management Ltd, to bring the site back into use as a £750 million green energy park.

Up to 100 full-time jobs will be created by the proposed park, which will be able to generate power to more than one million homes when fully operational.

Gary Lever, development director for BFL Management Ltd said: "The demolition of the cooling towers and chimney represents an important landmark in this project which will allow the site to be brought back into productive use for the first time in nearly 15 years.

"BFL Management Ltd is very excited to be developing a masterplan that will see this major brownfield site brought back into use as a green energy park.

"Our plans will combine the best in waste processing, recycling and green energy production technology.

"Up to £750million will be invested in the project and we hope that once operational the site could provide between 60 and 100 full-time jobs with an additional 500 jobs during the construction phase.

"When fully operational, the park could provide up to 1,400MW of power, including the output from the National Grid interconnector and Thanet Offshore wind farm, which is sufficient to power over one million homes."