She has been the talk of Twitter all this week thanks to a rather cute pixie haircut. Was it a wig? Had she really got rid of the mane like extensions? Well, yesterday the truth was revealed in all its glory when the incomparable Beyonce took to the stage at the V Festival in Chelmsford, Essex. She was, of course, brilliant, and, for fashion lovers, she also proved a visual treat, with a series of costume changes throughout her show. The hairstyle was no longer a pixie cut (which reminded me of when she played Etta James in the film Cadillac Records), instead it turned out to be a rather…