Strange insect

In the grounds of a garden I look after here in Kent, a friend is cutting down a large area of self-seeded, mainly birch trees. I went down to have lunch with him and he pointed out an insect that neither of us had ever seen before.

At first we thought, large wasp or hornet, but then realised it had two pairs of wings, more like a sturdy dragonfly, perhaps a broad-bodied chaser. The confusing thing is that it has stripes like a wasp but doesn't buzz like a hornet. There were several of them, basking on leaves and plant stalks. Anyone know what they are?

Chris

 

Thanks Marley for all your hard work, I really appreciate you taking the trouble. The Spotted Chaser seems the most likely candidate but I will try to have a closer look when I am next there.

Chris