I have a Wetherall dress in that same fabric! I love it--makes me think of tie silk... ;) My tag is different than yours--a red one, without the bond street address info.
I haven't decided exactly when my dress is from yet, but based on the silhouette (as well as the age of the other things I got from this woman), I'm waffling between late 50s and early 60s.
Here is an excerpt from a 1968 article (in a Calgary newspaper) about Wetherall, which was founded ca. 1870:
The House came into prominence with the First World War with the Greatcoat. Women who had been in the services found feminine clothes just too feminine after uniforms. The Greatcoat, designed with almost military precision, was a compromise then, and is still appearing in international fashion magazines.
Basic items in the collection in Calgary are reversible capes, coats, suits, skirts, blouses and hats.
‘We don’t follow fashion slavishly,’ explains Mrs Coyle. ‘We forecast and and follow trends of style.’
Wetherall colors are traditional also, says Mrs. Coyle. She feels British tastes are swinging from the garish, psychedelic hues to softer, more luminous shades.