We think this Lilli Ann jacket c 1949. White Paris-San Francisco label, & longer line & asymmetry more 40s than 50s brand #style. 1949 first ever rock and roll record, Lilli Ann well established relationship Paris. So teamed with veil hat Schiaparelli I restored same era. 
 
The jacket has possibly lost a button so had been worn with a brooch, which was damaged but I found one exactly the same, period. But certainly Lilli Ann suits often had a top jewelled brooch as button in the 1940s. Also there were lots of stencilled wool fibres under the collar so we think a collar had been worn with it, possibly to give a more sloping neckline as Lilli Ann under Jean Wright refused to abandon shoulder pads. By 1953 Billie Jeanne Dugan was at helm and much shorter jacket lines and exaggerated flare of peplums. So we think this a Jean Wright design. And certainly we found one very similar  asymmetry & pleated side dating from 1949. By time dorian Leigh is modelling for them early 1950s the nipped waist & flared short prplum have arrived. 
 
So the I Love Lucy Club of vintage fashionista experts may challenge me on this but I am going to stick my neck out for now! Only jacket similar seems to be 1949/50 season.
 
But whatever, its a piece of fashion history and if you buy it wear and enjoy but you are its curator, and will possess a very interesting piece to pass on to next generation to treasure,
 
It has no fabric label but is wool crepe, and lined with a very nice thick silk rayon sturdy georgette fabric in perfect condition also tailored which suggest French workmanship, so likely later than 1948. 
I would say a size 10-12 UK size just slightly too big for me as a UK 8 but an 8 could get away with it too. It is not pinned on me and looks ok. I am wearing with a bullet bra. 
 
You get the collar with it, as whether it was with it originally or added, it is nice to have. It is a faux fur made with wool which again is unusual web backed. Ribbon is later addition. 
 
In good vintage condition with no damage or stains at all even lining is perfect & pristine. Only top button/brooch is in question but when you see other Lilli Ann suits of the 1940s with brooches the same at top maybe not.