Mounting a sectional ladder vertically

[Capitol]

Before I start bending metal, has anyone seen lockable brackets for storing a ladder vertically?

[Martin Bonner]

Is there any reason not to use any of the lockable ladder brackets one above the other (rather than horizontal), and just not lock the top one?

Alternatively, a pair of brackets to hold the ladder, plus a padlock and chain fastened to a secure wall anchor.

(At the risk of stating the bleeding obvious, don't fasten the ladder in a place the tea-leaves can use it to access an upstairs window.)