Posted by Jon on 11/25/98:
At one time, they lived near Falmouth (where John and Susan learned to sail - pre-SA). I'd suggest St. Mawes, since at the time of Missee Lee, Commander Walker was still in Hong Kong and Shining Moon returned to St. Mawes. We know they were moving to the Shotley area as Commander/Captain (he's referred to both ways in SW) Walker was coming back from Hong Kong for an assignment there at the start of WD. I would expect that they either stayed around the last home-assignment base when he was sent overseas, or re-located to his new ship's home port.
Interesting that there doesn't seem to be any indication that he was ever stationed/based out of Scapa Flow, just along the Channel and south coast over the time of the books, although his ship was evidently ported in/around Sydney at one time in order for him to meet (the future) Mrs. Walker (ref. SA - she grew up around Sydney harbour, also IIRC in SD - John remembered the manouver he used to win a dinghy race in Sydney in the race with Amazon).
From reading other period books, I believe that even Portsmouth was rather close to the country, and obviously to small-boat sailing in the '30s. Professor Callum probably felt no overwhelming desire to get out to the country when he came back from months on archaeological digs, so Dick and Dot probably led town-centered lives wherever they lived (I vaguely remember London being mentioned in one of the books, which certainly would qualify as a town).