There should be a serial number stamped on the left rear fork end, perhaps consisting of an alphabetic letter prefix followed by several digits (7?) and then by a G26 for a girls 26" bicycle.
My wife's Evans EO49493G26. Unsure on year. Family I got it from suggested 59/60. Hoping if a bunch of us post numbers that maybe we can learn to decipher them.
thecabe.com
With some little guesswork, some attribute the letter "A" to 1954, after Evans acquired the bicycle division of Colson in 1953.
Not so sure myself though.
The twin top tubes complimented the boys cantilever frame, which was
not shown in a 1957 catalog excerpts (somewhere on this site?), so maybe later?
If not in mint condition, I might probably be satisfied just knowing the year, and assume a base model girls bike without accessories?
Evans also advertised a flamboyant Turquoise color.