Inside Wimbledon's new roofless Centre Court

For the first time in the tournament's history, Wimbledon's Centre Court is to be roofless - and that includes the royal box.

Open top: the first picture of a roofless Centre Court. A retractable roof will be ready in 2009 but for now even the royal box is at the mercy of the weather

The 13,800-seat showpiece is undergoing major construction work that will see a retractable roof fitted and the capacity increased to 15,000 by 2009.

But this year tennis fans buying centre court tickets are being warned to come prepared for being completely exposed to the unpredictable weather.

Wimbledon spokesman Johnny Perkins said: "Our message is: beware. We often have our own microclimate at Wimbledon - sometimes there is rain on one court and it's completely dry on another.

"But this year weather will be an even bigger factor and there will be very little shade or shelter on centre court, so we are advising people to bring plenty of sunscreen and an umbrella."

Chris Conroy, the All England Club's project surveyor, said: "This year, and for this year only, centre court will have the look of a Roman amphitheatre. Having no roof seems to make it look bigger.

"By next year the fixed part of the roof will be complete, sheltering the spectators, and in 2009 the retractable roof will be complete."

With less than three months to go before the 121st tournament, the 13½ acre grounds resemble a building site, with three cranes and more than 200 workers on site.

Mr Perkins said: "The last 10 years have seen major construction take place here such as the new court one and Henman Hill. A lot of thought goes into the presentation of Wimbledon and the moment the championships begin we will have the drapes in place.

"I expect some people will not even notice there is such major work going on, much of which will resume the day after the tournament ends in July."

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Cover up: the old-style Centre Court at Wimbledon

Meanwhile, Wimbledon officials are considering introducing technology this year that will decide definitively whether a ball is in or out.

The Hawkeye system, which involves high-speed cameras mounted around the court to help solve disputed line calls, has proved a success at Grand Slam tournaments.

Mr Perkins said: "It is being used on other surfaces and it is under consideration. The characteristic of the way the ball lands on grass is different, so we are testing around this area."

Security at the Championships is of paramount importance and the heightened procedures introduced last year after the terror attacks of 7/7 will again be in place.

The golf course across the road will be used as an area for security searches and fans hoping to take a picnic hamper on to Henman Hill will be advised of size restrictions.

Should the rain arrive during the second week, spectators can rest assured that Sir Cliff Richard - who famously entertained the centre court crowd with a medley of his hits on a rain-soaked day in 1996 - will be watching on centre court.

His spokeswoman said: "Sir Cliff will be at Wimbledon for the second week of the tournament.

"Whether he would sing in the rain I could not say - he has always insisted that the year he did that was a oneoff."