Mount performance matters more than caliber against fast jets

Would any British medium-caliber naval gun have been useless against fast attack jets?

No; effectiveness depends chiefly on mount agility, autoloading, and fire control rather than the nominal caliber alone.

The panel rejects the claim that a 4.5-inch, 5-inch, or 130 mm gun is automatically useless against a fast jet. Caliber is secondary to whether the mount can train and elevate rapidly enough to place the muzzle on target. Autoloading and fire control must then sustain the required rate and calculate sufficient lead. Large guns can therefore contribute as a last defensive layer when their mount was designed for the task. Historically, smaller weapons from 40 mm to 3 inches often made that agility and volume of fire cheaper to obtain.