I seem to remember a report that said the resultant blast would have the capability to wipe out most of Sheerness, and send a tidal wave up the Thames Estuary and across to Southend. You can weigh up the pros and cons of this.
The Olau line ferries used to pass pretty close to it when they sailed out of Sheerness.
Another fun fact - Boris Johnson's idea of building an airport in the estuary would have involved getting rid of the Montgomery. I can just imagine him in goggles, snorkel, flippers, and a rubber ring wading into the water saying "Be back soon chaps"