Here are my colleagues I can highly recommend you in other European cities. I have either my own experience with them or got a reliable personal recommendation.
Adrienn, your tour guide in Vienna: Adrienn is fully licenced guide for Vienna. Offers the tours in English, German and Hungarian language. She will show you Vienna from inside-out!
Gordon, your tour guide in Scotland: Gordon is experienced guide for whole Scotland. He also offers guide-driver tours to reach all the regions of this beautiful country.