It works, but I had to add a line break.
I'm not sure what version of footer I customised (most likely the vb3 beta one that I've been dragging through each update), but it had the <script block directly following the DST correction block:
</if><script
For some reason that I don't want to look into

, it would not recognise that as a JS block and was compressing it.
If I moved the <script onto a new line like thus:
</if>
<script
Then it worked perfectly.
As I said though... the footer template is one I modified in vb a long time ago... so this is likely not an issue as viewing the original now shows that they are indeed on new lines already and thus work perfectly.
If anyone has old templates that they've modified though, they hopefully will read this and add the linebreak