Britain's leverage at the Washington negotiations

What would have to change for Britain to secure everything it wanted from the naval treaty?

Britain would need to bargain harder and credibly threaten to walk away, since a naval treaty without Britain was unworkable.

Britain possessed more bargaining power than it used. Calling in American debt could have caused serious economic disruption, but the problem was not insurmountable immediately after the First World War. A credible willingness to walk away could therefore have extracted greater concessions.