I was in my local Decathlon this morning and discovered a bag they sell that is well worth sharing with RFF.
It's a small hiking accessory pouch named "2L Extendible Belt Pocket" which comes with a shoulder strap and coincidentally happens to be made to measure as a carry case for a Bessa R body with lens attached. My R3A / 35 2.5ii fits perfectly with the hood still attached so I imagine a longer barrel lens would be fine with hood taken off.
Plain black canvas material, rugged construction, very unassuming as a camera bag - all yours for the princely sum of £5.99.
This thing has answered my prayers after months of searching for something small, stylish, and practical, but without the price tag of a Domke etc.
(I have no affiliation etc, just passing on the bargain!)