Request #186

I’m looking for a young adult novel I read in the 1980s or early 90s. I think the book itself was from the 70s or 80s but could have been as old as the 60s. The story took place in a seaside town in England–I remember a lot of coastal imagery. The protagonist (I believe her name was Lindy?) is interested in sewing and fashion design. At one point, she refashions a nightgown and puts it on a mannequin, which is referred to as a “guy.” An old man is offended because he believes mannequin is somehow meant to mock him. At one point, Lindy is praised for catching a sea bream fish. This is all I can remember.