The shuttle unit is a Gaugemaster SS1, which is powered from the Aux of a redundant HM2000 analogue controller. The track power is also provided by the HM2K but from a speed knob controlled channel. The length of track is normal Hornby code 100. At each end one rail has a track break with a diode soldered across the gap.
The SS1 provides for adjusting the stop time before reversal. The control panel has been set up for manual or auto running.

Link to video -
https://community.hornbyhobbies.com/gal ... g_3296mov/