[I've added a little more refactoring](https://github.com/guardian/frontend/commit/33553ed419a7b1cf45cd51af49dd83d60c76130b#diff-ba8cb60a60f2af56bd81792f03f5c754R245) as what this was was a bit rubbish.
I will finish it off and apply it across the site after while deprecating preload-msg.