The UAV/Drone people are hinting at are Corax and Raven - some photos here:
https://ukdefenceforum.net/viewtopic.php?t=370
Howevet, these were pretty small having seen them. Around 15ft wingspan at the most. They led to the full sized Taranis that is about the size of a BAe Hawk. However, these are 21st century aircraft.
