I thought my mousepad had kicked the bucket as it'd stopped working even though Device Manager said it was working fine. Uninstalled drivers, reinstalled drivers and restarted to no avail.
Looked at my keyboard and noticed an odd icon resembling a hand pointing to a square with a
No icon. Held down FN then pressed it, lo and behold it works again.
The cat must've disabled it in one of the many times she's walked on my keyboard today.