Thank you Richard - and the others that also commented.
However, it was also little old me doing the Sound in Marquee 1 at Shrewsbury. The difference was that at Shrewsbury, there were a lot more loud bands on, each of which brought their own Sound engineer, and over which I had little control. We DID have a maximum sound level set at the sound desk and this WAS monitored, and we never exceeded the Environmental Health limit at the boundaries of the site (for those that are interested, this was set at 65dbA). But on several occasions, I have to agree it was bit over the top.
My obvious comment is, if you go to festivals that put on these type of artists, and you don't like loud music, you are going to be disappointed.
The difference between the 2 festivals was that Shrewsbury had a much bigger marquee, and the difference between sound levels front to back was more pronounced. It is always going to be louder at the front, but there are measures that we can introduce for next year which will minimise this.
I have to say that, despite the vocal minority who complained about Shrewsbury ( and I am not trying to devalue your opinions in any way), there were considerably more who have complimented us on the quality of the Sound. To paraphrase old Abe Lincoln, "You can't please all of the people all of the time".