Thanks everyone!. Plain brown sleeve - For such a major label in the fifties, this is so surprising, considering their 45's had the distinctive blue & white stripes design
I have a 10 inch London sleeve - see here. I got this on eBay, with my copy of London Calypso CAY 105. All the other few London 78's I have were in plain brown sleeves.
I believe that all of the post-war Decca Group 78 RPM labels came in plain brown sleeves, viz: Decca, London and RCA. The one illustrated on the link above will be from an overseas release.
Edit: I've just had another look; it must be from a very early London release c.1950
Edited by Strawberry_Lynn on 1st Feb 2013, 1:16 PM
Thanks fellow Sidney. I just linked it to a random London record just to show it. It's now safe in a plastic sleeve without the Decca disc that was inside