Pye 84 4097 television stabilizing amplifier.
A stabilizing amplifier would be used at various points in the transmission path to correct any errors in the sync pulses and blanking levels. They could be used to re-generate the signals or insert new ones from the station SPG. A typical use would be to correct the syncs on the output of a vision mixer.
This unit has 23 valves and a separate stabilized 285volt HT supply unit.