... flew almost every day in the Sunderlands ...
I'm jealous - I never saw an airborne Sunderland and am too young to have had the opportunity to fly in one. I have seen a Mars twice - once at a distance over Vancouver Island and then again at Oshkosh, where it did very impressive water drops on the airfield. I also travelled on a BC Airlines Mallard in the 70s. A colleague and I were traveling from Vancouver to Tofino airport. This was a round-robin trip, where the Mallard then flew on to Tahsis, a remote logging-community and then back to Vancouver.
The departure was delayed due to a mechanical issue - we could see, through the open rear door, a mechanic's legs as he lay head first in the tailcone! The captain came over to me and my colleague and asked, since we were the only passengers for Tofino, if he could fly to Tahsis first. So I got to experience a water-landing, taxi up the ramp and a subsequent glassy-water takeoff. We ran for over a mile!