Heinke helmet 6 nuts type Admiralty.
Rarely a Heinke helmet is in the best conditions like this, due to their are very old, underwent a lot of changes.
That unit, a part of their spectacular old patina, doesn’t have any modification, copper helmet, bronze plastron and bronze brails, everything identified with their number.
Heinke was allowed by Siebe Gorman to make the old model 'Admiralty Pattern' during the Second World War when Siebe Gorman did not have enough potential to provide the number of helmets that the Royal Navy needed.
Siebe Gorman was the only company who had the contract with the Royal Navy to provide helmets, but as the needs were greatest, Siebe Gorman allowed to Heinke to make a 6-pin plastron helmet identical to their system 'Admiralty Pattern', in order to have the possibility to be exchanged between them.
That’s why the central hublot has the same thread that a Siebe Gorman helmet, the central hublot thread from the 'normal' Heinke helmet 12 bolts are totally different.
Heinke only manufactured 500 units of this special unit, 'Admiralty Pattern'.
We're not sure if this was the only reason of Siebe Gorman couldn’t increase their production, because their factory was destroyed by German bombs in 1941 meanwhile Siebe Gorman was moving their factory from London to Chessington.