This unusual signal is at the north end of the southbound platform of Diss station in Norfolk. Crossovers at either end of the station allow northbound trains to arrive or depart from this side of the station, either to access the sidings or to reverse if the line is blocked. Signal CO433 controls trains starting northbound but is turned on its side so that it is visible beneath the platform canopy.
<a href="//commons.wikimedia.org/wiki/User:Geof_Sheppard" title="User:Geof Sheppard">Geof Sheppard</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>