The cost of making the Clyde a larger naval base

How viable would a larger Royal Navy base on the Clyde be?

It is physically viable but would require major expense; other locations such as the Mersey might be more practical depending on the requirement.

The Clyde is viable in physical terms but expensive to expand for a much larger surface-fleet role. The Mersey area might offer a more likely alternative depending on the political and strategic requirement. The answer separates geographic feasibility from the investment needed to make a base operationally useful.