Year – Not sure. From 1938 to 1959. The jumper looks war time to me, so I’d guess 1940s if it wasn’t a large format printed pattern in full colour.
Size – 34, 35 inch busts
Yarn Size – 3 ply
Marriner still exists as a yarn company and it can be found here.
What an exquisite pattern stitch down the front and sleeves. Shame these designs were made in one-size only; seems that would have limited their market potential.