Don't be scared.

This is quite harmless. It is a female Giant Horntail. It is also called a Giant Woodwasp but it is actually a Sawfly, not a Wasp. Scientific name is Urocerus gigas.

What people fear is a sting is in fact an ovopositor which the female uses for laying eggs usually in dead pine trunks. The larvae feed on the wood for up to three years. It is found throughout the UK.

I have to thank my friend P. for this shot. Whilst he and Mrs.K. were discussing clever computer mapping software I had spent half an hour searching for insects in his wonderful garden. But with little success. But on returning to his summer house they pointed out this little beauty on the inside window. I say little, but for an insect it is quite large.