The current issue of Model Rail (issue 187) has a number of signalling-related items in it, including:
page 6: Downloading a free signal box from 'Smart Models' and assembling it. The model is based on the 1956 'Low Gates' box - see http://www.signalbox.org/gallery/ne/lowgates.php.
page 36: Masterclass - Signal Boxes. A brief history on five pages, with photos, on signal boxes. Includes mention of the limitations on the distance that points could be manually operated, but doesn't give figures or the fact it was imposed by the BoT.
Page 41: GCR Signalbox Conversion. Kit-bashing an LNWR kit to make a GCR London Extension box.
Page 42: From card to stone. Adding relief details to a card signal box kit for greater realism, including detailing of the frame and block shelf.
Page 64: How To ... Install Point Rodding. Use of the Wills point rodding kit to give more realism to a signal box and associated layout.
Page 85: Subscribe to Model Rail and get a free Hornby Midland Railway signal box (limited edition model of one now preserved at the Barrow Hill roundhouse site).