It’s a pity really that most of the adventures of the Second Doctor, from season 4 to 6, were lost. Mainly because Patrick Troughton was a truly fantastic Second Doctor!
He’s more energetic, talks less and does more, and is faster on his reactions than his previous incarnation. He also has a very different relationships with his companions, which I felt was more dynamic and levelled.
Oh, I do hope they find all of his adventures, because, somehow, I just can’t watch the audio recordings with stills from the episodes… what a shame!