Sir Jock told BBC1's Andrew Marr Show: "There is clearly the issue of affordability in the round but there is also now the difficulty that we have which is we have a terms of business agreement with the dockyards. "The reason that this was reached was actually entirely sensible.
"To enable us to come down to one dockyard the industry had to invest in the necessary rationalisation.
In the 25-year existence of the Verolme Cork Dockyards, 33 ships were built and 1,500 men were employed at its peak.
The story of Verolme Cork Dockyard is told through the experiences of four men who worked in the Dockyard in various jobs - Paddy O'Keeffe, Danny Byrne, John Brennan and Donal Dilworth.
Spies monitoring communist activity at Chatham dockyard in the 1930s and 1940s would have appreciated the help of James Bond's gadget expert Q, it would seem.
Pc Ivan Smith used the covert spot to overhear proceedings at a meeting of dockyard apprentices discussing strike action in December 1941.
Pc Smith wrote: "I went to the A.S.E (Amalgamated Society of Engineers) Club Hall, Balmoral Road, Gillingham, and secreted myself in a lavatory of the cloakroom adjoining the hall, in order that I might overhear what was said at the meeting of dockyard apprentices."
Some nuclear dockyard workers were exposed to high levels of radiation, which may have caused them to contract cancer, while refitting Royal Navy submarines, the Ministry of Defence has accepted.
The Government has conceded after a long campaign by families of men who worked on Britains nuclear submarine fleet at Chatham Naval Dockyard, Kent, that there could be a link between illnesses suffered by former workers and radiation levels at work.