Thanks for posting this helmet.
I'm sorry to be the bearer of bad news to you about it. This helmet is one of the famous fake, modern era made in the United Kingdom helmets that was manufactured sometime in the 1980's or as late as the 1990's era. Everything about this helmet is modern made, including the metal parts, the helmet body, and the interior lining is all modern era made.
It sadly looks "similar" to what a WW1 era officer pickelhaube is supposed to look like, but there are many signs that I could list for you if you so desire, that clearly show to anyone who is familiar with what a real WW1 era pickelhaube actually looks like, that proove that your example really looks nothing like what the parts and helmet body and lining of an original era helmet is supposed to look like.
There seems to be an endless amount of these fake/replica helmets that were made back in the 1980's, and now that they are pushing approximately 40 years of age, they give the appearance of looking "old" because in the sense of having been made approximately 40 years ago, they are "old" in that sense. There literally must have been many hundreds of these produced back in the 1980's by whoever made them in the UK.
Best wishes to you.
Alan
