The unrotated projectile loses its rationale

Would the unrotated projectile launcher survive until a war beginning in 1942?

It would probably be discarded once possible, although British rocket research would continue along more promising lines.

The launcher's aerial-minefield concept retained influential supporters, including Churchill, despite its limited usefulness. More peacetime testing gives the Navy an opportunity to remove it before combat. British interest in rockets would survive the weapon itself. A radar-triggered rocket or early guided development is technically imaginable for the period, though unlikely.