The Spok is dead...

No, the Highways Agency only deals with Motorways.

The Highway Authority (who's responsible for maintenance) for this road is London Borough of Camden.

I should have been a bit clearer, my fault.

TfL should still have a look to see if they've got any info on Gower Street - they act as a kind of clearing house for reports of Street Faults, but LB Camden will be the ones to answer most of your FOI questions.

http://www.camden.gov.uk/ccm/content/contacts/council-contacts/transport-and-streets/contact-the-highways-management-team.en;jsessionid=07DE5A203142FA9389676E5E8F17332A

You're a legend - I owe you beer.