RISC OSMap of G.W. SignalboxesRISC OS
http://www.svrsig.org/gwmap/GWMap.htm
Sxxxx numberSignal Box nameView on map squareOther information including SRS diagram number
  Castle Bar Park Map BT155
TQ158819
SRS diagram not available
  Greenford East Loop Map BT159
TQ158835
SRS diagram not available
S 59 Greenford East Station Map BS159
TQ152837
SRS diagram not yet available
  Greenford South Loop Map BT158
TQ153832
SRS diagram not available
  Perivale Map BW158
TQ172830
SRS diagram S793
Prices are shown here.