For those brave souls still venturing onto the river despite the heat and sun, and the prospect of catching little or nothing, it's often a chance to have good go with the dry flies instead of nymphs. There will be some rises, often from Browns, if you wait long enough and find a shady place, even if it's almost impossible to cast to it, but that's part of the fun isn't it? Alternatively you can try for Grayling, but they don't seem to be too prolific either at the moment.
Personally, I like to stick to some old favourites when it comes to dries: a Grey Wulff is always a good start, or other Wulff variations, or a big blousy mayfly might just stimulate a rise. For Grayling I like the Double Badger, and for really picky fish, a Plume Tip might just do the job. Alternatively you can do it the professional way and try and identify what's hatching and imitate that. It's hard to know if you've picked the right or wrong fly, until you get a rise, or not.
There is one fly that is definitely the wrong one however.
If you spot this fly buzzing around you, or landing on you, I suggest you take evasive action immediately. These are usually known as Deer Flies, though some people call them Horse Flies. They will very readily suck your blood if they get a chance, and can even bite through a Tee or Polo shirt, and you may not even notice if you're busy fishing. You will certainly notice it a while later however as it turns into a big red swollen area and itches, and itches, and itches. It's worth spraying a bite with some Bite and Sting treatment straight away if you have it, but that won't eliminate the discomfort completely.
I saw one on Beat 2b recently, about to land on my hand, but quick and decisive action dissuaded it. They are persistent however, so drastic action is necessary if they target you, and stay alert.
Don't let that put you off deploying your own flies of course, and hopefully you'll select the right one.
PeterB