Why Sea Dart belonged forward on Invincible

Why not place Invincible's Sea Dart launcher and magazine at the stern?

A stern launcher would conflict with approaching Harriers and helicopters; the bow position gave pilots better warning of launcher activity and a less troublesome place to manage debris.

Harriers and helicopters approached from astern even when they did not make a conventional rolling landing. A stern Sea Dart launcher could therefore move or fire while an aircraft was already committed to its approach. The bow position used awkward space beside the ski jump, where pilots could see launcher movement and wait. That offered more opportunity to keep missile firing and aircraft movement apart. Missile-generated foreign-object debris was another consideration: no deck area benefits from debris, but some positions make it easier to manage.