Eventually a T-junction was reached (which was almost our limit of exploration). The right-hand branch led towards a collapsed gate, to a chamber where 2 shafts seemed to pass through - although they were both filled.
As we approached this area progress was very difficult as the level seemed to have a considerable amount of silt in it.
Looking at the walls the normal water level could be seen about 1.5m above our heads (so maybe the water levels were low!).
The walls were covered in a fine grey silt (tinted purple from the LED lighting in the picture left). Due to the silt on the walls and the depth of silt in the chamber around the shafts, we deduced that the silt was grout that had been pumped down the shafts and run out into the level and water.
Picture: Stuart Tyrer