Revert "Merge pull request #634 from alphagov/revert-sorn-page-update"

This reverts commit 0129b366c165ac47ef0352525b4d3b36fdd3a2fb, reversing
changes made to 872863c8f57f684b0404afdabccd2c3a5ec28937.

This reintroduces the changes made in #629 which were originally
reverted as DVLA weren't ready for them to be deployed to prod
Merge pull request #636 from alphagov/re-introduce-sorn-changes

Re-introduce SORN page changes