However the report on the BBC does suggest that we do have subs in operation with nuclear deterrent
'The problems do not affect the Vanguard-class submarines, which carry the nuclear Trident system.'
http://www.bbc.co.uk/news/uk-38931663
We've actually got a secret 8th ... which is also not operational?
He is probably right though, it will be something ridiculous like them all having maintenance and doing it at the same time saves costs. Probably also true that if they had to be deployed immediately then they could be. But...