Neddy Sawinson, Mrs Swainson and their youngest grand-daughter Mary Swainson produce butter and milk which Mary delivers to the market in Rio each day. The shipwrecked sailors get milk from her (SD10).
- "Bonny lass is Mary Swainson, aye, and a good wife she'll make and all." Jack reddened and then laughed too. (Old Billy to Jack the woodman, SD30)
She is romantically involved with Jack the woodman. THey see Mary Swainson talking to a youing man and Titty says It's the woodman (SD10). She sees Mary Swainson's woodman at the charcoal-burners' camp, and Young Billy says Bonny lass is Mary Swainson, aye, and a good wife she'll make and all (SD30). Mary and Jack (who seemed to have a day off) helped Captain Flint move the camp to the island (SD36).
Mary has an aunt who married a farmer down Preston way; she is going to visit her for a week, which she does every year. She is about to row to the village to catch the bus to the station, and thought of her Jack, who always fussed about her going away .... she reminded herself (when she saw the G.A.) that she was now grown up and was going to marry Jack the woodman, as soon as she thought fit (PM23).
She has known Miss Turner since she was a child, when she had been very much in awe of her. Now she smiled at Miss Turner (who had never married) with a queer mixture of kindness, pity and fear,. She gives her a lift to the island, then to the houseboat, and has to hurry to catch the bus (PM23).
It is not clear whether Mary lives with her grandparents because she is orphaned or in order to help them on the farm.
Mary's brothers wore holes in their breeches on the knickerbockerbreaker, as Roger does. Mary apparently darned theirs too (was their mother dead?) (SD15).
Links to Turner/Blackett family
When visited by Peggy and the shipwrecked Swallows, Mrs Swainson remarked that the Swallows ...don't look to me like Blacketts nor yet like Turners (so implying she knew both families). Mrs Swainson recalled a visit by Peggy's mother's mother. Old Neddy Swainson says: Sixty years. Sixty-five ... It’ll be nearer seventy (years) since I brought her up here from the church down by Bigland (SD9).