LONDON (AFP) - The first glimpse that the world gets of Kate Middleton at her wedding to Prince William on Friday could be under an umbrella after forecasters said there could be rain and even thunder on the big day. As a veteran royal enthusiast staked out his place in front of Westminster Abbey to ensure he gets a front-row spot, Britain woke up Tuesday to cloud-covered skies and signs that rain would gradually set in. Conditions on Friday when hundreds of thousands of people are expected to gather in London to see the couple are also likely to be much cooler than the sunny Easter weekend Britain has just enjoyed, the Met Office said. It is likely that southern Britain will see mostly cloudy skies with showery rain at times on Friday, a Met Office spokeswoman told AFP. In London there is a risk of some showery rain, but equally there may well be some brighter interludes at times. A brisk northeasterly wind could make it feel distinctly cool, she said. Aisling Creevey, a forecaster at MeteoGroup, said there could be some thunder during the wedding. It is looking at the moment that there are going to be quite brisk north-easterly winds, showers and possibly a few rumblings of thunder thats sneaking into the charts at the moment, she said. We wouldnt rule out the odd lightning strike as well. At the moment were waiting to see how much sunshine is going to come off that day. If theres more sunshine theres more of a risk of heavier showers. Rain would also affect global TV coverage of an event expected to be watched by two billion people worldwide. But if it does rain on the big day, it would give the crowd one treat the couple would leave Westminster Abbey in a glass coach that Williams mother Princess Diana used to travel to her wedding to Prince Charles in 1981. If the weather is fine then they will use an open-top horse-drawn carriage. Rain is unlikely to deter John Loughrey, 56, who was was the first to arrive at Westminster Abbey late Monday with only a sleeping bag and two carrier bags at the start of a four-day vigil to ensure a prime position for the wedding. He was dressed in a Kate and William T-shirt, emblazoned with the words Diana Would Be Proud with pictures of Kate and William tied round his waist and a Union flag hat.