Bourton
There are emergency crossovers at Bourton for the facilitation of Reversible Working (east to Uffington, west to Swindon East).
Interlocking
The interlocking at Bourton was commissioned on 1/10/77. The K2 refers:
The trailing crossover, enabling wrong-direction moves moves from Uffington and Swindon to return to the right line, was brought in to use on 2 November 1980 according to 31/2766. The routes from Uffington and Swindon were brought in to use in 1981 under 31/W/2770 and 31/W/2773 respectively.
SN.683R was converted from a 2-aspect (yellow/green) head to a 3-aspect (red/yellow/green) head at 0700 on 30 September 2001, although the red aspect was not brought into use.
Further Reading
More photos of Bourton: https://www.flickr.com/photos/swindonpanel/sets/72157645729888124/