Could very well be a WWII British Brodie helmet or a WWII British Turtle helmet, depends on the shape of the helmet. BMB or Briggs Motor Bodies Ltd of Dagenham is a known British company making WWII British helmets. Below is the Brodie style helmet list I have put together for identifying British/Canadian/American Brodie style helmets.
Known steel suppliers of the WWI British helmets:
FS = T. Firth & Sons Ltd Sept 1916 – 1918
BS = W. Beardmore & Co Ltd Jan. 1916 – 1919
HS = Hadfield Ltd Jan. 1916 – 1919
V = Vickers Ltd 1916 – 1917
MS = Miris Steel Co. Ltd 1916 – 1917
A = Edgar Allen and Co. Ltd 1916 – 1918
F = Thomas Firth and Sons 1916 – 1918
O = Samuel Osborne & Co Ltd. 1916 – 1918
B = Bury's & Co. 1916 – 1918
Known makers of the WWI British helmets:
D = James Dixon & Sons Dec. 1915
HW = Hutton & Sons Dec. 1915
HH = Harrison Bros. & Howson Ltd. Dec. 1915
M = J&J Maxfield & sons Dec. 1915
R = John Round & Sons 1916
V = W&E Viener Dec. 1915
MLS = ?
FKS = Possibly Thomas Firth & Son
M&S = Possibly Maxfield & Sons.
Known makers of the WWII British helmets:
BMB = Briggs Motor Bodies Ltd of Dagenham
F&L = Fisher & Ludlow Ltd of Birmingham
GSW DP & H = General Steel Wares Department of Pensions & Health
HELMETS LTD = Helmets Ltd of Weathhampstead
RO&Co = Rubery Owen Co Ltd of Leeds (Spelled as RO CO or RO&CO)
WD = William Dobson & Son of Birmingham
? = Patent Pulp Manufacturing Co Ltd
JSS = Joseph Sankey & Sons
Known makers of the WWII British liners:
VERO II
TTC 2
FFC II
FFL II
V.M.C II
"N" LTD II
HELMETS Ltd I (Helmets Ltd of Weathhampstead)
Known makers of the WWII Canadian helmets:
CL/C = Canadian Motor Lamp Co
AG/C = Aluminium Goods Co
GSW = General Steel Wares
Known makers of the WWII Canadian liners:
Baskstay Standard Co (Also made chinstraps)
Viceroy Manufacturing Co = C/Arrow or VMC
Known makers of WWI American helmets:
Edward G. Budd Manufacturing Co. 1,150,775 made
Sparks, Withington Co. 473,469 made
Crosby Co. 469,968 made
Bossett Corporation 116,735 made
Columbian Enameling & Stamping Co. 268,850 made
Worchester Pressed Steel Co 193,840 made
Benjamin Electric Co. 33,600 made
Known heat-stamp markings in WWI American helemts:
UC
YJ
ZA
ZB
ZC Columbian Enamaling and Stamping Company?
ZD
ZF
ZH
ZJ
Brodie Helmet picture:
Turtle Helmet picture:
