This will be filled up with available and upcoming design descriptions. For the moment here are some sketches how it works and expected performance:

Matthew J. Charles and Roger Forty
Publication as pdf   NIM A 639, Issue 1 (21 May 2011) 173–176

Detector: Schematic layout of the TORCH detector. For clarity, focusing elements have only been shown on the upper and lower edges. Photodetectors extend along the full length of each edge.
Concept: Cross-section of the focusing element (left), and definition of the angle θz (right). The focusing of photons is shown for five illustrative angles between 450 and 850 mrad, emerging at different points across the edge of the plate.
Performance: Identification efficiency of the subset of well-measured charged tracks which are well-matched to a primary vertex. The plots show the efficiency for a kaon (upper) or pion (lower) track to be identified correctly (black) or incorrectly (red/dot), considering only the kaon and pion hypotheses. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)