By Clare Purdy BBC News Online, Lancashire

Jayne Mansfield lit up Blackpool back in 1959

The Blackpool Illuminations are being switched on 125 years after that dim start.

The number of visitors is expected to reach 3.5 million this year.

The resort's six-mile light show equipment is now worth about �10m and is maintained by 45 staff all year round.

But organisers maintain that the principle behind the 1879 illuminations, and today's high-tech version, is still the same - to bathe the resort in artificial sunshine.

Eight arc lamps marked the start of the world famous attraction.

For many years the lights went out when the tide came in; water leaked into the cast iron pipes on the seafront.

The list of celebrities and famous names who have switched on the lights, reads like a who's who of the last 70 years.

The Spencers encouraged holidaymakers to visit the resort

Lord Derby was the first; footballer Stanley Mathews switched on the lights in 1951, George Formby two years later; Jane Mansfield in 1959; Rochdale's Gracie Fields in 1964 and Liverpool comedian Ken Dodd in 1966.

Sir Matt Busby was the famous face in 1968; the cast of sitcom Dad's army in 1971; Race horse Red Rum in 1977 and Terry Wogan in 1978; followed by the Muppets a year later.

The late Princess Diana's parents, Earl and Countess Spencer won over the crowds with their enthusiasm for the task.

In 1981, weeks after their daughter's wedding to Prince Charles, the couple declared: "You will never have a better holiday than in Blackpool."

In the last 20 years, switch-on celebrities have included: Lisa Stansfield; the Bee Gees; Westlife; Ronan Keating; Frank Bruno, and last year boyband Blue.

Illuminated history The illuminations shine non-stop for 66 nights Cable and wiring stretches more than 200 miles The amount of electricity consumed costs about �50,000 Illuminations which have gone missing over the years include an Egyptian mummy and Lego men The switch-on is always live when the button is pressed A worker for Colonel Gadaffi tried to buy up all the illuminations

This year former Spice Girl Geri Halliwell will be lighting up the resort.

The nearest to modern-day displays was staged in Princess Parade in May 1912, to mark the first royal visit to Blackpool, when Princess Louise officially opened the new section of the promenade.

An electrical engineer was instructed to decorate it with garland lamps.

About 10,000 bulbs were used and the results were so impressive that the local chamber of trade and other businesses persuaded the council to stage the lights again in September of that year.

Thousands of people visited and it was judged a success.

It was the start of the modern illuminations.

The next year, the council was encouraged to stage the light show again, but hopes of building on it were dashed with the outbreak of World War I.

The illuminations returned in 1925 on a more ambitious scale and by 1932 an animated tableaux was added, linking the North Shore with Bispham.

Government permission

The length of the lights was extended to its present length of six miles (10km).

The outbreak of World War II meant the lights did not come on for 10 years, returning in 1949.

But even then the council had to wait for government permission to use the required amount of electricity.

Now technology used includes electronic controllers, fibre optics and lasers.

This year's features include alien space ships forming a welcome arch, tiffany lamps, angels and devils, a video projection screen, a carousel, animated pirates, Alice in Wonderland, fireworks and a haunted hotel.