WW1 Anti-aircraft battery danger sign?

Came across this today, never seen anything like it before, and can't quite understand what the point of it would be. The colours match up with those used by the NER for station boards, brown and cream;

Lot 177

"A North Eastern Railway First World War warning notice A A B Danger "Anti Aircraft Battery - Danger" from Hartlepool, which was actually attacked by German warships and Zeppelins in WW1"

http://www.gnrauctions.co.uk/auction/2014-06-07

No affiliation with the site, seller etc etc, just a very curious member of public - and hopefully not another missed opportunity for inclusion in my book!

 

Yes - it is a genuine North Eastern Railway sign from Hartlepool dating from World War One.

Hartlepool, along with Scarborough and Whitby was one of the few British towns attacked by the Germans, mainly gunfire from warships offshore, but also by Zeppelin bombers inHartlepool's case.

 

Do you know which battery it referred to? I'm very aware of the Bombardment and Zeppelin raids on Hartlepool and have researched them

 

I have asked the vendor if he can supply any further detail and will respond if and when I am informed.

 

The vendor replies that the dredger masthead lamp and the enamel sign were acquired together and both originated from Hartlepool Docks.

I realise that this does not narrow the search down to one particular emplacement, but it does narrow it down to the docks estae.