Some more locations that I found:
RAF Welford:
51°28'33.1"N 1°24'08.8"W
Chaddleworth
https://goo.gl/maps/mw5khMU78yUe8xu28 - ATI HPSS?
51°28'00.1"N 1°23'54.6"W
Welford
https://goo.gl/maps/odcyeUS8DZfn9MpD8 - ATI HPSS?
Lucite International:
54°35'02.5"N 1°16'11.1"W
Stockton-on-Tees, Billingham TS23 1QG
https://goo.gl/maps/MXcHQ4djjuVVqZvX7 - Hörmann ECN 3000
Melrose:
55°35'56.7"N 2°43'29.8"W
High St, Melrose TD2 9RY
https://goo.gl/maps/4cF9jNXSjZX9Zj93A - Carter
Samlesbury Aerodrome:
53°46'37.9"N 2°34'03.3"W
Myerscough Smithy, Blackburn BB2 7LD
https://goo.gl/maps/oRAuVD7nAtpU9dcn8 - Hörmann ECN 3000
RAF Menwelth Hill:
54°00'56.9"N 1°41'08.4"W
Menwith Hill, Harrogate
https://goo.gl/maps/L39HRnJ97kR5zf7a7 - Mystery Siren
54°00'49.6"N 1°41'06.1"W
Second Ave, Menwith Hill, Harrogate HG3 2SW
https://goo.gl/maps/fJToVAgv7RMF546f9 - Mystery Siren
54°00'49.9"N 1°41'47.0"W
Menwith Hill, Harrogate HG3 2SW
https://goo.gl/maps/Zp8ni5phAKNZWpMZ7 - Mystery Siren
54°00'45.2"N 1°41'32.1"W
Menwith Hill, Harrogate
https://goo.gl/maps/ddxTot4zeuCurTfL6 - Mystery Siren
54°00'23.8"N 1°41'27.1"W
Menwith Hill, Harrogate
https://goo.gl/maps/dAVP7wMSFCUxMXXf9 - Mystery Siren
54°00'30.2"N 1°41'05.9"W
Menwith Hill, Harrogate
https://goo.gl/maps/E1K9tnuE4aVkLNidA - Mystery Siren
Humber Refinery:
53°38'47.7"N 0°13'07.6"W
South Killingholme
https://goo.gl/maps/5UML83cRbSJ2oRYK8 - Whelen WPS-2X05
53°38'16.8"N 0°12'15.0"W
Immingham DN40 2PB
https://goo.gl/maps/uVgP68RY5GBZWjsLA - Klaxon ES/Hörmann ECN
Sellafield Siren System:
54°25'11.5"N 3°29'24.4"W
Sellafield, Seascale
https://goo.gl/maps/8vPP7GuonU8ef4Hs7 - Klaxon ES?
HMS Rayleigh:
50°22'26.3"N 4°13'24.3"W
Torpoint PL11 2PD
https://goo.gl/maps/WUd9AWdepR9698y48 - ACA Screamer
RAF Molesworth:
52°23'01.2"N 0°25'03.0"W
Brington and Molesworth, Huntingdon
https://goo.gl/maps/ZAmp7RqHuXNbxy73A - Hörmann ECN
RAF Feltwell:
52°28'26.5"N 0°31'07.0"E
Feltwell, Thetford
https://goo.gl/maps/ze4Tp3qdrtpFd8278 - Federal Signal DSA 3X2
52°29'01.2"N 0°30'40.2"E
Feltwell, Thetford IP26 4HL
https://goo.gl/maps/km1LiP3W6YGaBMkWA - Federal Signal Modulator 2008?
Seen a: KM Europ, small Klaxon siren and a Gents' of Leicester "ahooga" horn.
Also a big fan of both Apollo and Protec fire alarms.