The New Zealand Railways Magazine, Volume 14, Issue 7 (October 2, 1939)
The Southern Railway has for some time operated the largest suburban electrification of any railway in the world. The latest development on this system is the conversion to electricity of the four stretches of track in Kent from Gravesend to Gillingham; Strood to Maidstone West; Swanley to Rochester; and Otford to Maidstone East. This electrification completes the ambitious scheme which comprised the Eastbourne, the Portsmouth No. 1, the Portsmouth No. 2 (Littlehampton, etc.), and the Reading extensions, and adds another 54 route miles—making a total of 702 route miles—to the Southern electrification. For the new services, some 152 coaches have been put into working, and greatly accelerated services have become possible—a most desirable thing in this busy metropolitan area. Between London and Chatham, via Strood, passenger trains have been increased from 40 to 49 daily, and the average journey time reduced from 76 to 69 minutes. Between London and Maidstone West, trains have been increased from 24 to 43 daily, and average time cut from 106 to 93 minutes. Equally striking improvements have followed electrification on the London-Chatham, via Swanley, and London-Maidstone East routes An interesting point about the coaches employed in the new electric services is the provision of duplicated periscopes, which allow of signals being observed by the guard when travelling in either direction These are called for because the width of the stock prevents the use of the usual side look-outs.