Sirens used in docks?

[IMR]

Hello, I run a hobby called London Sound Survey and did a blog post there recently about sirens in London:

London Sound Survey on sirens

There's a couple of warning siren sounds courtesy of Andrew Pollard, one of a maximum security mental hospital warning system, the other a flood warning system.

I mention a bit about dockyards using sirens, generally smaller machines, either electric or hand-cranked. A friend who used to live near the docks in the 1960s told me about this, but I've not been able to find out any more.

Does anyone know about sirens used in docks at all?

Thanking you in advance
Ian

[Tannre]

Is there a Klaxon CS siren by that hospital? I remember seeing a video of one of those Klaxons near some mental institution.

[CJ]

There's a system of Klaxon CS's for the Broadmoor mental institution. They do hi-lo.

[IMR]

The Thames Flood Barrier also sounds a steady all-clear tone with sirens when it raises the floodgates into position.

Not the kind of event you can predict far in advance though, otherwise I'd have recorded it by now.