How old battleships deterred convoy raiders

How much difference did old Royal Navy battleships make when protecting convoys?

Their heavy guns created a deterrent: a raider might win locally but take damage that prevented its escape.

The escort did not need to outrun or destroy the raider outright. Its 15-inch guns made a close attack dangerous to a Deutschland, Hipper, or Scharnhorst. Even a German tactical victory could leave the raider damaged and unable to escape stronger British forces converging afterward. The old battleship protected the convoy by making the attack's likely cost exceed its immediate reward.