On a side note if anything I would have thought the Sontarans would have been a bigger threat to the Time Lords since they were time traveling long before the Daleks and even invaded Gallifrey in Invasion of Time.
When did we find this out? What I remember is, The Chase
had Time Traveling Daleks and The Sontarans weren't even introduced until Late Pertwee. Meaning we'd need a specific reference
One Day I hope to be the Man my Cat thinks I am
Where are we going? And why are we in this Handbasket?