SOLVED. A book about 2 sisters one called Lindon, she was a cookery student and got a good job with a rich family. [s]

[Claire]

i read this in the late 80’s
Two sisters one overweight and shy nothing goes right for her the other sister called Linden was a cookery student.

[Mai]

This book I found searching AbeBooks.com fits your description:
The Windmill Years by Vicky Martin (originally published in 1978).
Anna and Linden were sisters, although no one would have guessed it. For where Linden was coolly beautiful and poised, Anna was overweight and terribly shy. But both were to find that life, and love, could be more complicated than they could imagine.

[Claire]

Thanks so much!!!!