Been waiting a long time to do this one. Thanks to some great advice from certain individuals and some persistence, it was a great explore! It's one of those places where you feel very aware of how easily things get forgotten over the course of time. Brilliant day out. Pic quality's really not the best; all were taken with a compact and built in flash. 
Some history courtesy of SubBrit:
'On 23rd September 1941 Shorts Brothers contacted the Ministry of Aircraft Production regarding their seaplane works at Rochester seeking authority to build a new underground works in tunnels excavated under chalk cliffs behind their existing MAP extension factory on the south bank of the River Medway. Space was urgently required for 75 new machine tools as their works were full to capacity. The tunnels were intended to create 12,000 square feet of workshop space at a cost of £20,000 which, it was acknowledged was somewhat higher than a new surface building but stress was lid upon the vulnerability of the Medway estuary.
The project was given the go ahead and the tunnels were excavated consisting of two parallel tunnels, each one hundred metres in length, these were linked by four 75 metre long adits to the cliff face at the rear of the factory. The tunnels were for the most part cut from chalk and brick lined (one of the adits was unlined). There were also two 45 degree ventilation shafts extending to the surface.
Post war, the southern section of the tunnels was used for storage and workshops by Blaw Knox Ltd, contractors plant manufacturers, (a subsidiary of the Babcock International) who had taken over the former Shorts Site. They remained at the site at least until the mid 1990's.'
Thanks for looking!
Vertex
Some history courtesy of SubBrit:
'On 23rd September 1941 Shorts Brothers contacted the Ministry of Aircraft Production regarding their seaplane works at Rochester seeking authority to build a new underground works in tunnels excavated under chalk cliffs behind their existing MAP extension factory on the south bank of the River Medway. Space was urgently required for 75 new machine tools as their works were full to capacity. The tunnels were intended to create 12,000 square feet of workshop space at a cost of £20,000 which, it was acknowledged was somewhat higher than a new surface building but stress was lid upon the vulnerability of the Medway estuary.
The project was given the go ahead and the tunnels were excavated consisting of two parallel tunnels, each one hundred metres in length, these were linked by four 75 metre long adits to the cliff face at the rear of the factory. The tunnels were for the most part cut from chalk and brick lined (one of the adits was unlined). There were also two 45 degree ventilation shafts extending to the surface.
Post war, the southern section of the tunnels was used for storage and workshops by Blaw Knox Ltd, contractors plant manufacturers, (a subsidiary of the Babcock International) who had taken over the former Shorts Site. They remained at the site at least until the mid 1990's.'
Thanks for looking!
Vertex
