Spotting

Notes:

It was flying around in our garden. It has a long sting, but i don't know if that is specific. It was crawling around on the ground for a long time and seemed to want to lay eggs in the space beetween the stones. It was large, i first thought it is a hornet, but the color and shape doesn't fit. Perhaps some kind of Ichneumonidae, but i can't find it anywhere. Can anyone identify it?